Covert flirting between two people. Because they have to keep their true feelings for each other secret, for whatever reason (i.e. they work together, one is married, etc.).
"Those two can't seem to stand each other! They're always fighting over something!"
"Wrong, man. It's all a front they put up. They're actually macking on the sly."
Opening up a set with previously unknown individuals. The intention typically being wanting to sleep with said individuals or "randos."The tactic is often used when working day or night game. Masters of this trade often don the nickname "Rando Mack."
Randy "Hey man how was the party last night?"
Mike "Pretty sweet man, you know, just spent the night mackin on randos."
Randy "Nice you get any numbers?"
Mike "Nah."