Someone who constantly repeats the same lame joke they've already told you 3,000 million times before, expecting that the 3,001 millionth time you're bound to laugh.
Retarded Monkey Fuck: Hey, what's brown and sticky?
Other Guy: I don't know, jackass. Why don't you tell me?
Retarded Monkey Fuck: A stick! Haha!
Other Guy: I'm so glad I have zoloft...