A weapon, usually a gun. Refer to your "girlfriend" before a fight and watch your enemy falter. By calling your weapon your girlfriend, you are indicating that you are so fucking crazy you think you have an intimate, loving, even sexual relationship with your weapon and cherish it and will kill anyone who messes with it. Thus, it implies a love for fighting and getting buckwild on cowards.
Never leave me baby, I'm paranoid
Sleepin with you loaded by my bedside, crazy
Jealous when you hang with the fellas, I wait patiently alone
Anticipating for the moment you come home
I'm waitin by the phone this is true love, I can feel it
Had a lot of women in my bed, but you the realest
So if you ever need me call, I'll be there through it all
You're the reason I can stand tall, me and my girlfriend
Q: Why the hell did Pac wait by the phone for his gun to call him?
A: SEE WHAT I MEAN IT MAKES YOU LOOK LIKE A WILD ASS KILLA