Those black opaque tights that girls where, mostly in college and in the colder times of the year. They really flaunt the postirier and the crotchal region in the front.
When I go to the college cafeteria, I feel like i could stick a finger up every girls butt through those butt pants.
Pants or shorts so tight they reveal the shape of the wearer's posterior in provacative detail.
When you first see Ramza in Final Fantasy Tactics, you are at once enthralled by his conspicuous buttpants.
Any pants (usually jeans), most often worn by women but can be worn by men, with no rear pockets, intended to accentuate a person's butt...whether it be big or small.
Ricky: Yo dude, check out that fat ass!
Bobby: EEWWWWW man, that chick does not need to be wearing butt pants!! A few pockets would go a long way in concealing that shit.
Pants which grab a man's ass to the point where you can almost see their balls from the back. Cowboys tend to wear these with cowboy boots and a fuckin' retarded ass hat.
BIlly: Yo ted, you see that cowboy over there wearin' butt pants?
Ted: Fuck dude, that's disgusting.