Perry Steffensen
Perry Steffensen voted up Levi F.'s answer
Why does Flanderization {The act of taking a single (often minor) action or trait of a character within a work and exaggerating it more and more over time until it completely consumes the character.} occur and how can it be prevented?

It happens a lot in comedies because writers think the character is only funny when that trait is present. So they emphasize it more, then it becomes exaggerated, then it completely consumes the character, often to the point that it ruins the character and ceases to be funny.