MJ'd

The articulate process by which a drunk and horny female, mostly of the promiscuous type in a relationship with another man, grabs the shaft of the male genitalia (aka a boner) with one fist, and then stealthly with the other hand grasps the left or right gluteal while thrusting said male genitalia inside of the vaginal cavity (aka pussy). Girlfriends are not counted in this particular process.

(Dumbed down version)
When a down ass bitch grabs your dick with one hand, your ass by the other, and slam dunks that shit straight into her pussy.

Mj'd is when you're a man who leaves his current girlfriend because you discover you are gay.