Hiring unpredictable – and some might say, ‘unstable’ – pop star Britney Spears as an X Factor USA judge must have been something of a gamble for Simon Cowell, and yesterday, after she stormed out of her first day judging auditions, he was perhaps regretting his decision.

Britney reportedly decided she’d heard enough when one wannabe “murdered” one of her tracks, and without warning, she simply upped and left, leaving the audience chanting “Where’s Britney?”

However, she later tweeted, “LOL was just taking a little break people. I am having the best time.”

But onlookers begged to differ, claiming that Britney was unhappy with the audience’s reaction to some of her comments about the hopefuls’ auditions…

One claimed that after being jeered, Britney then resorted to using just one word when asked for her opinion of the auditions, such as “amazing” or “adorable.”

The Sun quotes one audience member as saying, “She was like a rabbit caught in headlights.”

However, Britney’s shaky start to her new role was apparently covered by the banter between Simon Cowell and guest judge, 19 year old singer Demi Lovato, who reportedly flirted throughout the seven hours of filming.

Demi apparently called Simon “grandpa” and he told her she’d have to sit on “the naughty chair.”

So that’s what they’re calling it these days…