'X-Factor' -- All Four Judges Walk Off!

All four "X-Factor" judges just pulled a Britney and high-tailed it off set, TMZ has learned, after witnessing the worst audition in the history of auditioning.

Sources at the taping in Kansas City tell TMZ ... Britney, Demi, L.A. Reid and Simon Cowell's stand-in, Louis Walsh, couldn't stomach one more second of a certain wannabe superstar's "singing" and were so disgusted by it ... they walked out mid-audition.

We're told it all went down because the guy auditioning walked on stage, claimed to be "better than Chris Brown," and then turned his back to the judges to sing with his eyes closed. After a few bars of melodic torture, the audience started booing and the judges peaced out.

The judges all eventually returned, we're told, but Britney need a little extra time to get over what just went down.