To Au Jus someone: Basically, the female version of tea bagging.
One must be female, and it is the gentle dipping of one's labia (beef curtains) into the mouth of the receiver, who may be male or female.
Much like the gentle dipping of an Arby's sandwich into delicious Au Jus sauce.
Bitch #1: Hey ho, how was your night last night?
Bitch #2: It was great, I was Au Jus-ing Alan all night, and he loved it.