The "Aux" at the party is the owner of the music device currently plugged into the auxiliary cable, thus controlling the parties groove.

the act of anal sex

aux is referred to Auckland city, the largest city of New Zealand.

Narrowly averting a catastrophe by coming up with an ingenious plan.

From the Apollo 12 moon mission. The ship was struck by lighting on liftoff and its electronic systems went out of whack. A Flight controller named John Aaron told the flight director to have them switch "SCE to aux". This fixed the problem and saved Apollo 12 from being aborted.

The blood and lifeline of a Car trip it is handed around the car so that all the homies can partake in playing there sweet jams you until some shitter plays Nickleback then the aux cord is immediately yanked and not to be returned to said homie.

That one friend that always sits shotgun and takes the aux without asking the squad.

when your playlist ends and it starts playing random songs.