When I lived with roommates we would always come up with contest. Like who could go the longest with out a haircut, or who could eat the most unknown meat out of a plain metal can. We never bet any money in these contest, all we won is pride knowing that we bested our roommate.
If you ever took part in a strange contest to win nothing, please share them via a comment. I want to be assured that my roommates and I were not out of our minds.