To slaybitches with ones cock,
See also Mack King: so slay multiple Bitches with ones cock whilst wearing a crown
"I got carpet burn from macking this bitch"
"I shattered her boxed whilst slaying the bitch, I am the MackKing"
"Penglis Got his mack on with two other guys"
To mack someone is to post comments about them on their friends my space pages. This could involve starting rumors or getting something of your chest.
Thus leaving the person in question, completly embarrased about what you have informed he/she about, in relation to themselves.
E.g. I just macked your ass and told fred you like him! Or, You just got a good macking of him/her, now everyone knows.