A friend or co-worker whose only objective in life seems to be looking for funny (or supposed to be funny) stuff in the net and then force you to look at it together with him.
.George: "I can't believe they haven't fired Mark yet."
John: "I fear the editor in chief is starting to love all that goddamn spam stuff he keeps mailing to the whole office all the day... That's what an e-joker does."
George: "Oh... Ok. I'm off."
Mark:"Hey George, did you checked your e-mail recently? Huh? Huh?"