A term for someone's anis that is being used for other purposes than natural bodily functions. The term is typically used for those that do this quite often and with different partners or inannimate objects.
It describes how the ass, what is supposed to be a used for dumping, is mostly used for something being dumped into it.
Tommy has such a dirty garbage can, everyone and everything has been up in him.
Dude, I donno if you want to get up in her garbage can, it's full if stink!