motorboat

To ride in a motorboat.

(slang) To press or bury one's face between the breasts of a woman; to press or bury one's face between the breasts of a woman and shake one's head, hum, or vibrate one's lips in imitation of a motorboat engine's sound.

(slang) To press one's face into or between (something else).

(slang) To press or envelope someone else's face into or between one's own breasts; to wrap one's breasts around someone's face or head.

Any vessel driven by an engine (either inboard or outboard), but especially a small one.