'X Factor' Judges Let Them Eat Cake!

6/9/2012 8:34 AM PDT

'X Factor' Judges -- Let Them Eat Cake!

Simon Cowell picked a bad day to call in sick for "X Factor" auditions -- because Britney Spears, Demi Lovato and fill-in judge Louis Walsh enjoyed cake backstage yesterday in Kansas City with the birthday boy ... L.A. Reid.

As TMZ previously reported, Britney really stepped up her game with Simon out -- despite almost falling on her way into the arena -- and was tough on contestants when need be. Simon is not expected to be healthy enough for today's round of auditions.