When a woman places a single breast on the ass of a man. This will result in the most mind-blowing, ball-draining explosion of man butter ever. Boob on ass.
Mike: "Dude, I Teriyaki Phonebooked Chelsea last night."
Todd: "What the fuck are you talking about?"
Mike: "She put her boob on my ass."
Todd: "Ohhhhh. Nice, Mike."