Ripped by Random Talking Bush.
The Dirty Upper, also known as EWJ punch, is Earthworm Jim's anti air move in ClayFighter 63 1/3 and ClayFighter: Sculptor's Cut. He leaps into the air and does an uppercut, kind of like Ryu's Shoryuken.
This may be a reference to Megaman in Marvel vs Capcom: when he was introduced into a fighting game from a platformer, they gave him the move of their most famous fighting game character. When Earthworm Jim, a character used to platforming games was put into a fighting game, Interplay gave him the shoryuken.