This is when three guys fuck one girl in the same hole, physically impossible yes, but the “bitch dick” would belong to the guy in the middle of the two other dicks. Similar to riding "bitch"(the middle of the back seat)in a car.
A guy with a very small cock. This person may have been a female (homo) at one point in time. Also known as a needle dick, popsicle stick, and or tooth pick.
Nick: Is that a guy or a girl?
Chris: I don't know but it has 2 belly buttons.
Nick: Ah...no dude thats not a belly button thats a bitch dick.