Bitching out a dumb ass hoe; is where you bitch at her cause she's a two faced bitch, who has no heart, uses people, and will sleep with anyone/anything that has a dick!
In the 60's and 70's the word "bitchin" was often combined with the word "ass", as in "bitchin-ass", used to describe the ultimate, supreme, primo, or a hot looking sexy girl.
1.Wow check out that bitchin-ass chick!
2.Man last night we smoked some bitchin-ass weed.
3.We had such a bithin-ass time at the concert.