Sandra, a slumber party is a pajama party/sleep over with a bunch of (usually) girls. But, of course, you rarely get much sleep. We always watched horror movies and told scarey stories. We played with a ouija board-with disastrous results. LOL There's lots of trouble you can get into at a slumber party.
TP'ing is a slang for toilet paper. When one tp's something, it means that you spread toilet paper all over something. It's very, very commom around Halloween. We usually get our back and side yard trees toilet papered every year. It's so dark in our back and side yard that we'd never see anyone back there.