similar to after grad, only before a graduation as opposed to after. Basically sought after by the kind of douchebag high schooler who believes the only way to enjoy themselves and prove to their friends that theyre the shit is to get wasted, even if it means making a complete fool of yourself in front of your parents and teachers at the actual grad ceremony.
Normal guy: Ohhh man im gonna get sooo wasted at after grad
Douchebag: Ohhh man im gonna get soo wasted at pre grad, then sneak in some booze for grad and get wasted there, then get totally wasted at after grad. yeah im the shit.