Here is my favorite contract story.
There is an instructor in my city. The guy has been teaching for a very long time, but he has a couple screws loose. I know, because I trained with him for a short time. The night when he punished us with pushups for two hours for no reason, and then started screaming at the voices in his head, was when I stopped going back. But somehow, he has managed to train some fierce people. True story. I'm not making this up.
Anyway, My wife also trained with him, but years after I left and before we met, and she knew people who continued to train with him years after she left. So here is the contract. He decided that he wanted to start training a group of teenagers and young adults who he felt showed promise. So he created a special training group for them, meeting several nights each week for intense workouts. In the meantime, he basically abandoned his class of adults, some of whom were studying with him for years. Everyone who agreed to be part of this group paid for the whole year in advance, non-refundable.
As part of the agreement, the students agreed that they absolutely would not miss a session. If they did, then they had to pay a penalty of something like $25. If they did miss a session, they could appeal their case to a body of their peers, who were pressured by the teacher to deny the plea. A friend of my wife missed a session because the traffic on the bridge after work was clogged due to an accident. She was caught in the traffic and just could not make it. Of course her plea to the board fell on deaf ears.
So these people pay for a year in advance, and they pay again if they don't show up. This guy is a business genious. I should take lessons.