Credit: FOX Photo: Demi Lovato X Factor Promo Shot

Simon Cowell was definitely the mean judge on American Idol, but on The X Factor, he's got some major competition from 20-year-old pop sensation Demi Lovato.

An X Factor source told E! Online that Demi and Simon joined forces during the Denver auditions when a Miami native showed up to sing — and butcher — Rihanna's hit single "Only Girl (in the World)."

The contestant appeared before the Simon and Demi — as well as Kelly Rowland and Paulina Rubio — in a skintight black dress and clutching her iPhone. Why did she need the iPhone you might ask? To apparently read the lyrics of the song she was auditioning. Sounds like she was off to a terrible start.

Regardless of whether she needed her phone to tell her the lyrics, she didn't perform well for the judges (surprise, surprise), and Simon was the first to let her know it. "You remind me of when I am outside a night club in Vegas at 5 a.m. and there are drunk girls leaving the club singing," he told the girl. "It sounded a lot like that."

Demi took it a step further, adding, "I agree with Simon, actually. I feel like you're kind of the reason I don't drink anymore."

Ouch, we're definitely looking forward to seeing that audition!

Source: E! Online