An altered state experienced by participants and/or fans of a sporting event which render them incapable or rational thought. It can occur before, during, and after the event. Face painting and conspiracy theories are all examples of people experiencing competition psychosis.
Dude 1: Can't believe how those refs were cheating my boys.
A competition in which a man does not shave his beard of cut his hair for 1 year. During said year people who dared the man to enter the contest, provokes him to shave his beard and thus losing the competition.
Seth Rogen's friend in the Movie Knocked Up, dared him to enter A Dirty Man Competition by convincing him if he succeeds his roommates would pay his rent, if he fails which he did he would have to pay everyones rent