Joke lamprey 

A person who tries to claim a funny thought, or joke as their own when they either had nothing or very little to do with it.

Guy 1: Did I tell you about the new sex position I came up with, I call it the Lazy Astronaut.
Guy 2:Dude you did not invent that I already read about it on the Urban Dictionary.
Guy 1:ummm yea I was the one who posted it
Guy 2: B.S. man! I know the dude that invented it! You are such a Joke Lamprey...

Joke lamprey by Salmonhq February 13, 2008