said person isn't a "wuss" or is badass in some way. This can refer particularly to an instance in which someone is drinking, smoking, or doing something extreme.
Tom: "I bet you cant drink another shot" -offering another shot of vodka
Jim: "Daddy aint no bitch" -takes shot without puking
Joseph Tinnelly used it to argue with Gordon Ramsay in The Hell's Kitchen
Gordon Ramsay: "unbelievable one simple request who and, why and you make a big song and dance"
Joseph Tinnelly: "I ain't no fucking bitch, Chef. I don't give a fuck! I ain't no bitch!"
a common phrase you use to express the fact that you aren't a bitch, pussy, wuss, etc... Commonly used when you want to want to do something you normally wouldn't do on a limb.
guy 1: there's no way in hell im going outside
guy 2: fuck it i ain't no bitch
*goes outside and suffers in the cold, but fuck it at least he ain't a bitch*