NBC censors caught the five planned expletives in rock band System of a Down's (search) "Saturday Night Live" performance — but a sixth, unscripted swear word slipped through.

Toward the end of the band's performance of "BYOB" on Saturday, the camera caught guitarist Daron Malakian (search) screaming out an expletive.

NBC said it had asked the band to remove the swear words in their lyrics, but the band refused. Network censors eliminated the audio when the expected expletives were said. The unscripted swear word, heard on the live East Coast telecast, was edited out for other broadcasts, NBC said.

NBC has had trouble with late-night rock 'n' roll previously: Motley Crue's Vince Neil once used an expletive during a New Year's Eve telecast and U2 lead singer Bono used one during last year's Golden Globe Awards, which were broadcast live.

A spokeswoman for System of a Down did not immediately return a phone call seeking comment Monday.