1) The act of ditching prior social obligations.
2) When someone gets pissed off over some little/insignifigant thing.
2) Man, Pat started trippin and bitched out over some damn toilet paper!
Alex bitched out of the fight after he saw his opponent was clearly bigger
Person A: there's no way that girl is going to bungee jump
Person B: yeah I'm betting she is going to bitch out
Person 2: What a bitch.