It means the activity of putting one's face between a woman's breasts, and rocking turning one's head rapidly from side to side while making a noise like a motorboat.
"Put your head between her tits and go bbl bbl bbl bbl bbl..."

An exclamation made when your friends or family are teasing you to a point where you can't handle it anymore and a hissy fit is in order.

Derived from a YouTube user's famed outburst following Britney's lackluster performance at the 2007 VMA's.

The placement of one's face, specifically the mouth, into the area between a well-endowed woman's breasts, followed by a rapid shaking of the face in a side-to-side motion accompanied by yelling. The resulting sound that is created sounds similar to an outboard boat motor.

Sticking your face between a ladys fun bags and blowing hard allowing the boobies to wobble on your cheeks.

The act of making an engine noise when sticking your face in a woman's BOOBS.

A great way to end an awkward conversation with a girl you don't want to talk to.

The act of making a monotone hum while pinching and moving the cheeks back and forth