mack is a flexible word as a verb; it can be used in pretty much any situation and its meaning will be understood.
1. to make out with
2. to fool around with
3. to do everything short of sexual intercourse
4. to display acts of public affection
1. I saw you macking with her in the back of the movie theater!
2. Quit mackin' with me, baby.
3. They were macking like bunnies. Very horny castrated bunnies.
4. One should never mack in a public parking lot! If you're in the car, though, that's okay.