A wash-up is someone, whose best years are over, a worn out has-been, who is past his prime and over the hill.
Heckler: "It is not funny, that's why you're a reject, never had no shows, never had no movies, 'Seinfeld' - that's it!"
Michael Richards: "Oh, I guess you got me there. You're absolutely right. I'm just a wash-up. Gotta stand on the stage."