The guy was talking about bitchslapping a guy instead of hitting with a closed fist, saying the other guy was a bitch. Well, when he wanted to hit with closed fists, that was always an option, so was slapping each other around like bitches, and calling it a bitchslap, or anything else. It really all depended on how much more badass than the other guy he felt, if he felt like fighting in the first place.
when you slap the sense into a bitch because they keep fucking around
Person A: Hey, Person C, I heard Person B was messing with you again. What'd you do this time?
Person C: I bitchslapped that hoe so hard her teeth almost got knocked loose.
Person A: Uh huh...