OBB stands for Ooga Booga Bullshit. When 'people' get mad they 'chimp out' thus making the ooga booga sound, similar to a gorilla, then carry-on with bullshit. Usually senseless violence accompanied with 'angry noises'.
Person A sees person B starting to 'chimp out' in their general direction.
2. backronym for "Jail Outside Bars," the idea being that having to perform alienated labor is as oppressive, in its own way, as being in prison. One is in a kind of "jail," even though one is "outside" of any physical "bars" that would force you to stay there.