1. It is the description of an action that is so gruesome they had to cram all the words together to make sense of it.
2.Kill-A-Bitch is describing the act of beating someone senseless, putting them into extreme and unimaginable pain, or actually "killing" them.
Dude 1: Man watch where you walkin' man!
Dude 2: Well then get yo' fat ass out the way then!
Dude 3: Hahaha my man bout to killabitch!!
Dude 1: Man I was playin' halo 3 and this noob was tryna act hard in shiit. So i had to killabitch to let em' know, this aint no fxckin cowboy movie.