A female that is used to end to end a period lacking females. A slump buster is, generally speaking, less than what one's standards would be, had the person using the slump buster been in a time flourishing in the female department. It is usually looked back upon as a mistake.
Sean: Dang, did you see that fat chick Josh was making out with?
Jared: It's fine, we've all had our fair share of slump busters.