With your ball sack stretched over the mouth and nose of the receiver you then grab the base of your cock and slap them between the eyes and forehead with the tip. Works best when erect or semi pudged.
Zach: Dude did you see that? I BatSlapped LB so hard it left a red mark on her forehead.
Guy 1: I just batflamed your mom!
Guy 2: Did you hit a homerun?
Guy 1: No, I shoved a baseball bat into your mom and now she's disfigured.
Guy 2: Aw shucks... She was a bitch anyway