A phrase yelled at someone to show that you despise them and think that their mother is a whore. It is a phrase used by certain awkward, big nosed people when they are angry. One way to anger such a person would be to, for example, inadvertently hit said person in the testicles with a frisbee. This phrase is best yelled while attempting to kick whomever hit you with the aforementioned frisbee, although the kicking can be rendered useless by your target keeping you at a distance with his long arms.
*Person 1 accidently hits the awkward person in the testicles with a frisbee.
Person 1: Oh shit dude, i'm sorry! Are you alright?
Something you say when someone is being annoying. When you respond with "Chill a bitch", you are basically telling the person to chill out and shut the fuck up.
Jane: OMG, I am so scared. We are watching Chainsaw Massacre, omg is this a true story? Omg~
Adam: Chill a bitch. Seriously.
Jane: Is it a true story, tho?
Adam: ...Yes.
Jane: Ahhhhhh!!!
Adam: Heh heh.