motorboat

v. int. The act of pushing one's face in between two ample breasts, and rocking one's head side to side very rapidly while making a vigorous, lip-vibrating "brrr" sound.

n. The sound produced when doing a motorboat.

To submerge ones face in large breasts and moving your head back and forth, flapping your lips, in turn making a motorboat sound.

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A male or female who places their head between a female's breasts and shakes back and forth while humming, producing a sound similar to a motorboat in water.

the act of placing one's face between a woman's breasts and quickly shaking your head in a "no" like gesture left to right while emulating the sound of a motorboat.

An engine propelled seafaring vehicle.

a motorboat involves a girl with breasts large enough for a human head to fit between them. The owner of the head then proceeds to blow out of their mouth vibrating their lips. This action will make a sound very similar to a motorboat engine, hence the name.