Cap

From Rap Dictionary

noun

cap

1. Bullet. "I'm a pop a cap in him" -- Samuel L. Jackson as Jules Winnfield in the movie "Pulp Fiction"
2. Scalp, at the top of the skull. "Blood's on my gear, from caps I've peeled" -- Ice-T. (Mic contract [1991]).
3. Crack.
4. Penis.
5. to lie.
6. A kill. A gangstah who has killed two persons has made two caps.