Motorboating

[Tina]

The placement of ones face, specifically the mouth, into the area between a well-endowed womans 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.

[Justin Bieber]

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

[Sonia]

A great way to end an awkward conversation with a girl you dont want to talk to.

[Britney]

The action of sending an Ugg Boot sailing away in a motorboat for being so sinisterly ugly.

[Marquetta]

It means [the activity] of putting ones face between a womans breasts, and rocking turning ones 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...

[Jason Yan]

When a man [grabs] his penis and sticks it through [the crack] between a womans boobs as if he were doing [the real thing].