The act of swaping chewing tabacco while passionately kissing your boyfriend/girlfriend. Try french dip w/side of au jus where you use your sex partners anus/vagina as a spittoon for an extra nicotine buzz.
After meeting Mary Jo at the local smoke smoke shop where she bought a pouch of "Chattanooga Chew", Johnny invited Mary Jo to his hay loft for a french dip. Mary Jo responded with "Can I have extra au jus on the side"?
A guy goes to the bathroom, leaves the seat up and doesn't flush the toilet.
Then a girl goes to the bathroom, and without really looking or thinking, sits down on the open toilet seat.
Since the seat was left up, she falls in. Her labia "dip" into the dirty toilet water, and as they do, she exclaims, "Au Jus serious!?!"
Thus: the french dip
The Situation had just peed in the toilet and he left the seat up. Snooki was drunk and she went into the bathroom for a pee. She fell into the toilet, and she french dipped into the dirtytoilet water.
After smothering your mouth in a woman's au jus, you procede to place her natural roast beef back in your mouth, rub it around and then decide to continue eating. Repeat as often as you want to enjoy your meal. NOTE: Double dipping (SEE DOUBLE DIP) is permitted, and is in fact encouraged.