During a fight or an altercation, if one of the participants is knocked unconcious the victor (or a spectator) places a wallet in the victims mouth so as to prevent him from choking on his own tongue. Usually after getting wallet mouthed the victor ends up getting a free victory fuck from the loser's girlfriend.
He got wallet mouthed after talking trash to an arabian bear fighter. Subsequently Alex's girlfriend couldn't walk straight for a week.
Any girl you fuck on the side besides your girlfriend.
The old bar down the street is good for huntin side slash if your ever bored with your girl.