What is Mack It?
1.
To kiss passionately with someone for an extended period of time; commonly "to make out"
This phrase can also describe sexual relations beyond kissing
Often used as a conjoining phrase using "with" and a noun
I was mackin' it with some girl at that party last night. She was HOT!
2.
Verb.
Derived from the term
Kelly: Paul, can you pass me my pen?
Paul: Sure. ::passes pen::
Kelly: Thanks.
Brandon: Mack it!
Kelly: Shut up, Brandon.
Paul: Who's mackin' it now?