I can't believe this dude had the GUTS to talk the way he did UNDER OATH during his court deposition for attacking a photog...but WHAT set Bieber off during it?

Simple. Selena.

The lawyer for the photog simply asked if she was present during any of the alleged attacks, and Justin flew off the handle. Stormed out of the room screaming "Don't ask me about her. DO NOT ask me about her!"

A little while later, he came back in with his typical d-bag smug Bieberness. Justin answered "yeah" to a question, to which the lawyer responded "Do you mean yes?" Biebs comes back all like "What the F*** is the difference between 'yeah' and 'yes'?!" (Which I agree with, but really...show some respect ya tool.)