During the peak of the dot-com boom, I had a small but thriving software development company. We had a client who had an "absolute urgent need" to get some features on a product done within 30 days, to the point that he would constantly call or email somebody in my company asking if there was any way to speed up the process. For the budget and the feature set, 30 days was already pushing it, but since it seemed so important to him, I decided to shuffle some employees around, work myself to death (and also lose a bit of the profit in the process), but we were able to get it done in two weeks. Exhausted, but very happy with ourselves, my little team demoed it to the client, who was extremely happy with it, which of course made us feel even better about what we did, that is until he hands us a check, for half the agreed amount. His reasoning was since the project only took half the time, he should only pay half the amount. We eventually collected, but never again would I try to be THAT nice.