Basically, a bag of wine(has to be cheap, franzia acceptable) talks some shit to you. Being a person of class, you don't appreciate the aforementioned shit talk, so you beat the fuck out of the bag by punch. Upon punch you undo the nozzle and suck the life juice out of the bag until you can not take any more. Then you boot. (see def. of boot)
Dude.. I can't play slap bag, I have to be awake at some point next week. ...."SLLAAPP BAGGG"