bop ya bag 

"bop ya bag" is a phrase that some rappers (most notably OB-1) use in their songs. It refers to the act of bopping your bag, which is essentially smashing yourself in the testicles with a hammer. This activity is normally associated with the hyphy scene and other hip hop fans and is seen as the most extreme activity that one can engage in while getting retarded or thizz.

OB-1's song "bop ya bag" be slammin like a mothafucka. He be gettin mad stupid up in dis bitch an mothafuckaz be boppin they bags while listenin ta his jamz nadamsayin?

bop ya bag by Bag Boppin' Billy August 12, 2007