Simon Cowell's Advice to 'X-Factor' Rejects ... Try 'The Voice'

Simon Cowell thinks just because some singers are talentless, superstar wannabes not worthy to compete on "X-Factor" ... it does not mean they wouldn't be perfect for ... "The Voice." OH SNAP!

Sources who attended the Austin "X-Factor" auditions tell TMZ ... Simon and L.A. Reid came up with the brilliant idea to mess with the NBC show by convincing bad singers to audition for "The Voice" instead.

L.A. Reid was overheard on set telling one such wannabe, "If you decide to try out again, please do it on another show." To which Simon added, "Yes, the good news is I hear 'The Voice' auditions are happening next week."