I love reading Robin Hood-esque stories, which is why I found this thread from Quora asking, "What was a loophole that you found and exploited the hell out of?" It just goes to show that humans are too dang crafty. Here are the best ones:

Universal

1. "In January, the landlord complained about heating costs being too high. We thought we had been flexible enough. We were doing his reasonable austerity measures, and were paying the same rent as we had in September–November. Heat was supposed to be included in the rent. Landlord asked if we would do 50ºF (10ºC) for days, and 60ºF (10ºC) for evenings and overnight. We declined. Not reasonable. We were paying for heat. There was a discussion and some negotiation. Then, that landlord made a strategic blunder. One day, he said he would be doing maintenance while we were in class. When we came home, we discovered that he put a locked plastic box over the thermostat, and had set it for 50ºF (10ºC). Colder than cool. It was frigid in both the rooms and the kitchen. Doing that while we were out for class had been a mean and dirty trick."

"Not to be outdone, we got a plain old bucket. Canada, as you might expect, has snow from sometime in December until mid–late April. Our standard practice became for the first person going into the house from class and the last person going out for the day to hang a bucket packed with snow on that locked thermostat box. The landlord just couldn’t figure out why his costs went up, and why we stopped complaining. That bucket of snow kept that heat-controlling thermostat thinking it was FREEZING in the apartment and kept the furnace running just fine."

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—Ian Smith

Steven White / Getty Images/iStockphoto

2. "When I was 10, my parents signed me and my younger siblings up for the Krispy Kreme Doughnuts Kids Birthday Club. Basically, I gave Krispy Kreme my address and birth month, and they would send me a coupon for a free dozen doughnuts every year on my birth month until I aged out of their Kids Club at age 12. This is just for kids, OK? Sweet deal. But Krispy Kreme forgot to ask for the year in my birthday. They have no clue how old I am. So, I’m now almost 25, and I’ve been a member of the Krispy Kreme Doughnuts Kids Birthday Club for 15 years. That’s 180 free doughnuts for me, plus another 180 for my sister, and 180 for my brother. 540 free doughnuts."

—McKayla Kennedy

Scott Olson / Getty Images

3. "Every year I purchased McDonald's Trick or Treat books. These books sold for $1 each and had coupons for 12 “free” items like ice cream, burger, apple slices, yogurt, or fries. The idea was to give one of the coupons to each trick or treater that showed up at your door. They were good until December of that year. About 10 years ago, I purchased my customary 10 books and noticed that they did not have an expiration date! I went back and purchased an additional 50 or 100 books. (I forget how many, the store was sold out of them when I got done.) We used those books for YEARS! I still have a couple of coupons left waiting to be used. There was NO AGE RESTRICTION and NO EXPIRATION! The missing expiration date meant that ALL McDonald's had to honor them no matter what the month or YEAR."

—Christine Koch

Nurphoto / NurPhoto via Getty Images

4. "This professor gives weekly quizzes and monthly tests in person, but via the computer. We sign into a special software that doesn’t allow us to search the internet, and take the test with him there. Everything was multiple choice. But here’s where it gets interesting: Many of his questions had more than one answer. So, he set the test so you could check as many answers as you want (e.g. we could select both A and B because the answer could be both). But the test never counted how many answers we selected, and it only made sure you checked the right box, not if you checked a wrong box, too. So, if the answer was A and B, and I checked A, B, and C, it would count as right. So, what’d I do? I checked A,B,C,D, and E for almost every single question. The software would see that I checked the right answer (because I checked every answer) and mark the question right."

—Anonymous

CBC

5. "What did this customer do? Walk up to my till with a basket of shopping, followed by a whole tray of avocados; I reckon about 30 of them, which I dutifully scanned, slightly bemused. 'Perhaps they just really love making guacamole,' I thought. These particular avocados were nearly out of date so were heavily discounted from £1.00 to 10p each. A pair of avocados was now a bargain at 20p. Now, it turns out our avocados were also on offer. Not a great offer, just buy 2, save 50p. However, the till system was apparently dumb and didn't take into account reductions before applying this discount. This customer clearly knew that bug existed. So those bargain avocados looked even more delicious when the 50p discount made them cost -30p a pair. I stared in amusement as the -30p discounts rolled in and their shopping bill became smaller and smaller and smaller, until everything they bought was essentially free."

"They walked out of there smiling, and I sat there, pondering just how dumb the checkout software writers were."

—David Edwards

NBC

6. "In the early '80s, I tried a couple frozen TV dinners made by a company called 'Taste-o-Sea.' These dinners cost $.99 each and consisted of two rectangular breaded fish patties, a small bunch of tater tots, and a compartment of green peas on an aluminum tray (remember, this was almost 40 years ago). Well, they were nothing special, but hey, they were only a buck. A funny thing happened when I saw that there was a 50-cents-off coupon printed on the inside of the box they came in. Back then, Stop & Shop doubled coupons of less than a dollar. I bought the first five or so dinners with actual money, and then ate about five or six per week (work lunches mostly) for the next year, all paid for by doubling those coupons printed inside the box. I figure I got 200–300 free dinners that way."

—Marc Pellerin

CBC

7. "This actually happened to my father. His Lexus was stolen right out from his carport. Not sure if he left the keys in it or how it got taken. He reported it as stolen to the police and turned it in to the insurance company. After two weeks or so, when the car never turned up, the insurance paid him for the car. Another week goes by, and he gets a call from the police saying they had found his car parked two towns over in the middle of town. There was not one scratch on it and not a lot of miles put on it either. So now, the insurance owns the car, and they put it up for auction. My dad goes to the auction and bids on his car to get it back. He won the bid with $10,000 to spare. He drove home in his car with an extra $10,000 in his pocket."

—Pam Wilson Hansen

Europa Press News / Europa Press via Getty Images

8. "One time I went to the mall and stopped by my favorite ice cream booth. I never really liked the idea of two scoops of ice cream — it just seemed like a waste of an extra dollar since it’s harder to eat, and it can get pretty messy. But I saw that two of my favorite flavors were available: mint chip and bubble gum. I didn’t want to pay for two individual scoops, so I came up with an ingenious idea to get both. I went up to the counter and asked for half mint chip, half bubblegum. The counter lady looked kind of confused, but then proceeded to scoop up two scoops of the different flavors. At the checkout counter, they had no choice but to charge me with the price of one scoop."

—Catherine Wu

Picture Alliance / dpa/picture alliance via Getty Images

9. "In the late 1980s, I was an intern at Apple. They had just released the Mac II, the first color Mac, and the machines were basically impossible to get. As an intern, I was eligible for what Apple called 'first discount,' buying a machine at a substantial savings. I forget exactly what the savings was, but it was about 50–70% off. So the $8,000 machine would only cost about $3K AND we could get it immediately. The only catch is that everyone only got ONE first discount, so we had to use it wisely. If you bought something now, you would never get another in the future. I wasn’t planning on getting one since I already had a machine provided by work, and I didn’t have the money anyway. But then, a family friend who owned a small business asked if there was any way I could get a machine since his local store had no availability. I told him I could buy it with my first discount and explained how it worked."

"He was super appreciative and paid me the full price for the machine. WAY more than my discount. A few weeks later, as the intern season was coming to an end, he contacted me again, asking if I could get another machine somehow. I tell him I only had that one discount, but I would ask around. I asked some of my roommates and fellow interns and explained the situation, and someone let me use their discount as well. When I got paid, I split the extra cash with this person. I had a few thousand dollars for doing basically nothing.

At that point, the floodgates opened.

I systematically went down the list of all of the interns, finding people who were not using their first discount and would be willing to give it up. I offered them $500. Many people were happy to take it. Meanwhile, I got a list of 'clients' who were willing to pay OVER market price for the machines in order to get them quickly. I focused on customers who wanted the highest end possible so the price (and my discount) was maxed out. These were also the hardest machines to get, so people would gladly pay a premium for quick delivery. I moved about a dozen machines before the list was tapped out. It took about a two months."

—David Vronay

Nurphoto / NurPhoto via Getty Images

10. "I bought a new Lexus GS 300 in 2000, and it had been paid off for years, when in 2012, I parked it at a clinic, and when I got outside, a flash flood flooded the car. The insurance company towed it to a storage yard after them telling me that the car was totaled because the navigation system had shorted out and to replace it would be $9,000, and the car was only worth $8,500 or something like that. When I asked what they would do with the car, they said sell it and they would probably get $1,500 from a salvage yard, so I offered them the $1,500, and they wrote me a check for $7,000. I picked up the car, and the next day, the navigation system was working fine. I paid a detail shop $150 to clean the entire car inside and out and drove home with a very nice, clean car and $6,850 in my pocket."

—Neal Elinoff

ABC

11. "About 40 years ago, I bought some land and built a house on the land over a period of about a year. When I purchased the land, the county evaluated the land at the purchase price. After the house was built, my total investment in the property was about 10X the land price. Well, the county never reevaluated the worth of the property, and I paid about 1/10 the property taxes that I should have. I contacted an attorney after the first year and asked about the ridiculously low property evaluation. He assured me that the relationship between a taxpayer and a government taxing authority is adversarial. I had no obligation to tell them of their mistake. His advice was to take the difference between what I thought I should pay and what I was paying and put that money into an investment account, which I did. He said that if they ever caught their mistake, they might, might, try to get back taxes plus interest."

"After 14 years, the tax evaluators finally caught their mistake and changed the evaluation to a reasonable amount. I started to pay a reasonable amount of taxes, but no word about any back assessment. I think they were embarrassed about their laziness.

That was 25 years ago, and I think the issue is never going to come around. I left the investment alone, and today that $56K I put away is worth $400K. Thanks, government."

—Dave Brunfeldt

Picture Alliance / dpa/picture alliance via Getty Images

12. "Back in 1986, People’s Express airline had a $19 one-way fare flight from Boston to NYC. On Friday nights, there was a flight every 90 minutes or so, and they were all oversold. I’d book the 7 p.m. flight, show up at the airport, and when they asked for passengers willing to give up their seat in exchange for a seat on the next flight *plus* a voucher for a roundtrip flight anywhere they flew, I’d be the first volunteer. I used those vouchers to fly roundtrip from NYC to London nearly every weekend for several months, all for the low, low price of $19 (plus train fare back to Boston from NYC)."

—Kim Scheinberg

James Marshall / Corbis via Getty Images

13. "When I was in college, there was a fruit vending machine that cost 25 cent/fruit. One day, all I had was 25 cents, so I would get an orange which would have to last me all day. I put my 25 cents in and got an orange. As I turned to leave, I heard coins dropping into the coin return slot. It was 50 cents. Though very confused, still I took that 50 cents and got another orange — this time, the machine returned four quarters. So, I pocketed 50 cents and dropped another two quarters into the machine. I stood at that machine for damn near 15 minutes and managed to accumulate $6 and a dozen apples and oranges."

—Dragonechilde

CBS

14. Finally, "When I was younger, my dad was a single parent. Mom passed away from lupus. He was trying hard to make ends meet and had a part-time job at Burger King. He would volunteer for extra shifts and get food to take home if he did. The manager liked his drive; he worked twice as hard as anyone else. There was a scratch game they had going on at the time that allowed you to try to match prizes to win it. A free Whopper, fries, or drink were the choices. If you scratched off ones that were alike, you won. I discovered by accident the high-power spotlight my dad used in his shop was perfect for cheating. Put the light behind the ticket and you could make out the outline of the prizes! A winner every time! I showed my dad, and he just grinned. He asked for some after each extra shift. I did say the manager liked him, right? Well, he would get at least 10 each time! We ate a lot of Burger King that summer!!!"

—Terry Johnson

Fox

OK, if you've ever exploited a loophole, I want to know about it, so tell me in the comments below or whisper it to me using this 100% anonymous Google form