"Fuck" is never okay on American network and basic cable shows. We have a watershed, sort of, or SNL would be even lamer than it already is, but it's more like midnight than 9 pm, there's an exception for programs that families watch, like awards shows, and violence is much more permissable than s-e-x or profanity. (Exception: sex is okay as long as it's rape, a la the infamous Law and Order "sodomized with a violin bow" case. America: our values are fucked UP.)