Knock-Knock Fest

The rapping of one's knuckles across perky breasts-a way to please yourself by drumming your hands on a girl's front. Arousal is usually expected.

Matt: "So how'd it go with Jack last night?"

Danielle: "Well, we had a bit of a knock-knock fest, and now I'm all sore. But he's in a better mood than ever!"

Matt: "Okay, then."