A word that has lost it's real meaning thanks to white people.
verb. To make one's labia's move from either one's vaginal muscles or air being pushed out. Also the rhythmic movement of the buttocks as a result of flexing a certain group of vaginal muscles (see Kegel) in order to create the labia movement made famous by strippers.
For some reason this has been diluted to the any dance that moves one's buttocks but is hilariously interpreted by anyone who knows the real definition, usually people from the south or inner city.
Daughter: "Grandma watch me twerk it!"
Father (Horrified): "NEVER EVER SAY THAT AGAIN"