When a girl, typically a weird one, puts her vagina on your knee and starts to ride it vigorously until she climaxes. It usually does nothing for the guy and his knee thats involved.
Elizabeth-I wanna have an orgasm.
Me-Okay..I can help with that!
Elizabeth-Let me ride your knee.
Elizabeth-No don't watch the movie! Watch me give you a sexy knee job. I've had a lot of practice.
Me-Uh-mm.. this is doing nothing for me.
Elizabeth- Sh-shh! I'm almost done!