Fighting words. Used as an insult.
A person who has committed a small act of bitchery. The connotation is similar to that of a bro, brosky, homie, or boy- but this is the girls version.
Girls in a club
Stranger 1: *spills drink on stranger no. 2*
Stranger 2: You wanna go, Bitch-slice?
example two (small act of bitchery between friends)
Friend A: That was your ice cream? Sorry... I kinda ate the last spoon...
Friend B: Ugh, you bitch-slice.
example three (between friends)
Friend 1: WASSSSSSAPPPPP bitch slice?!
Friend 2: AHHHHH QUE PASO!??