1. To have sex from behind (can be either vaginal or anal)

2. Ideal for stimulating the g-spot or prostate.

When you're having sex, and the guy pulls out too far and accidentally thrusts into your asshole.

anal sex, up the bum, driving on the dirt track.

A very brave bloke who sat for hours in the rear gun turret of a WW2 bomber having the shit shot out of him by enemy fighters. It was lonely freezingly cold job with a high mortality rate.

When you are extremely rich like some music artists, and you are dumb enough to put TVs in the head rests of the seats in the back row of your car so "the people behind you can watch when you stop at a red light."

1. the posterior end of something

2. the buttocks

3. for one car to back into another