When there's hair growth around the nipples. A natural occurrence for all genders. Also referred to as boob pubes.
Have you ever lost a stiffy taking off a bra? She had some black and thick bupes.
When your buddy slams on the vehicle brakes when climaxing in the back seat with a partner. Causing the unbeknownst partner to clench their orifice while a significant and uncontrolled thrust is applied. Causing your seed to shoot as if flung from a sling shot. Very similar to the donkey punch but with the added thrusting jolt.
Hey man, we're going to lie down in the back. When I give the signal give me a brake pedal, will ya?