when you sit on the toilet and the shit rockets out of your anus, completing the "dump" in mere seconds
Dude 1: I have to take a dump.
Dude 2: Ok man, go. I'll wait like five minutes for you outside...
FFFRRRRRRTTTTTT!!!!! SSSPPPPLLLLAAASSHHHH!!!
Dude 1: Done.
Dude 2: HOLY SHIT MAN, THAT WASN'T JUST SOME DUMP! IT WAS A TURBODUMP!!!