to accidentally smush a pack of cigarettes, and then proceed to smoke one of the mangled cigarettes
(John Wayne often had a bent cigarette in his mouth in the movies)

during oral sex the man removes his member from the girl's mouth and slaps her across the face with it

Marijuana. Specifically, a significant quantity of high-grade, or sinsemilla, especially for personal use.

To not show your true feelings as you deal with an unpleasant situation. To be a "tough guy".

refering to someone as an "arse-hole"

first used in an episode of the scottish comedy "chewin the fat"

The "John Wayne" maneuver occurs when you and a male friend are both engaging in vigorous sexual intercourse with a female (one for each of you) in the position commonly known as "doggy-style". One of you is the cowboy, the other is the Indian. Immediately before ejaculation, you both withdraw your penises and shoot your load at each other. The first one to be hit by a drop of semen is the loser, rendering the winner "John Wayne".

Getting slammed (shot) from behind when your not looking (usually used in online video games). The cheapest way to get a kill since your opponent has no idea where you are and does not have a chance to fight back.