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"
n. A variation to common drinking game involving boxed wine. Someone holds the bag while the drinker chugs as much wine as possible. Sometimes a countdown is involved (and therefore a competition for most time on the bag). The slap occurs AFTER the drinker is done drinking. The bag is formally passed on to the next drinker.
"A Corp party is not a party without a little Franzia and some slapbag."
n. A drinking game using boxed wine. The bag is removed from the box and held by one person while the drinker slaps it as hard as they can before they drink. Most often associated with Franzia boxed wine.
"Dude, the party was weak until somebody busted out the Franzia. We played slapbag all night."