Compulsive Behavior is a mental, mundane disadvantage, described in Basic Set, pp. 128-129, which gives the examples Compulsive Carousing, Compulsive Gambling, Compulsive Generosity, Compulsive Lying, Compulsive Spending, and Compulsive Vowing. It is referenced in GURPS Fantasy™, p. 219, which gives the new variant Compulsive Debating.