The act of taking a shit in a toilet already filled with shit because either
A.) It has become clogged or
B.) You're having a Double Stacking contest
J: Man, I was at Ray's the other night and had to take a monster shit, but when I got to the bathroom, the only toilet was already full of putrid shit!
DOOKIE: NO! What'd you do man?
J: Well I tried to flush it, but it just spun around a bit. There was no way I was gonna make it home without squirting all over myself.
DOOKIE: Dude, tell me you didn't....
J: Yep, I just Double Stacked it.