The phrase was came about when a certain Philadelphia radio star, began acting as a monkey doing an impression of the actor James Mason, just moments after being told that the "Putty-Nosed" Monkey can convey verbal concepts. This is a defensive maneuver to fend off predators.
A person who begs for the attention, acceptance and approval of a certain group in different things they say. In most case, it's to attain the attention, acceptance and approval of the opposite sex.
Woman: *lives her best life*
Pick Me ass bitch: "I don't drink, smoke, or have sex with random people like all the other females out there. Guess men only go for hoes instead of real women. I'm not like other girls..."
Pick me ass bitch is someone who likes to act like everyone else in hope that they'll gain a friend/boyfriend/girlfriend. Tries too hard to be everyone's friend. Always underneath someone's ass and is willing to make others look dumb just to be around someone's company.