This is actually not dirty. It refers to the interference during the Cubs almost-win in the World Series. It is a Chicago slang term. It refers to the man who "knocked" the ball out of the glove of a player that "cost the Cubs the World Series".
Ya you know, da guy who cost da Cubs da World Series, dat guy's a jerk-wad ball toucher. Dat's what he is.
by Everything's Rosie April 09, 2009