butt swirlie
A variation on the swirlie where, rather than shove the victim's head into the toilet, the victim's bare butt is dunked into the bowl while the toilet flushes. Not as gross as a normal swirlie, but creates a weird and uncomfortable sensation. Often given as a way of taking a big wedgie to the next level.
I was just in gym class and those asshole jocks Luke and Pete gave me an atomic wedgie and a butt swirlie in the locker room after they beat me in dodgeball. As soon as they got my underwear over my head, they pulled my pants down and dunked my whole butt in the toilet and flushed. And they said if they win again tomorrow, they'll give me another, plus they'll flush my face too. This year is gonna suck!