American Idol judge Simon Cowell refused to make a karaoke cameo on Ricky Gervais' TV show EXTRAS because he can't sing. The music mogul has broken thousands of young hopefuls' hearts with savage appraisals of their vocal talents, but he admitted to The Office star Gervais that he too struggles to hold a tune. Gervais says, "He said it was the one thing he couldn't do. I wanted him to sing (SIR Elton John track) DANIEL and he told me, 'I can't do it darling.' "He said he'd do anything but that."