When you put your mouth on just one boob, make a sound like a jet-ski, and bob your head up and down to simulate a jet-ski hitting waves, flattening the boob out with your face each time you land. It's not quite a motorboat...it's a jet-ski.
Henry removed the hooker's bra, seeing that she had miscellaneous crumbs and what appeared to be crusty cum stains between her titties, he opted for jetskiing that bitch instead.