To gang up on a victim with a group of your mates to violate them. Usually a male bonding experience see when out drinking usually at the end of the night when the only way to achieve sex is by brute force with a bunch of your drunken mates. Can also be uses to threaten friends when they drop there nuts.
I'm so fucked shall we just Pac Rape that girl at the end of the bar?
Fucking do it or we will come in there and pac rape you.