In Con Law, we read FCC v. Pacifica Foundation (438 U.S. 726) from 1978. The Supreme Court decided the FCC was allowed to regulate profanity on the radio. My prof played the George Carlin broadcast that was the target of the case for us today in class (anyone who didn't want to hear it was invited, respectfully, to leave. Naturally no one did.)
Carlin informed us that there are 400,000 words in the English language and only 7 that you can't say on television. In the interest of free speech, I will cite them here:
Shit fuck cocksucker motherfucker cunt piss tits.
(Carlin on "tits": "What's that doing on the list? It's like the name for a snack! Nabisco Tits. Chedder Cheese Tits. Pizza Tits.")
The court said these words had such slight social value that they deserved less protection. The court's beef really was with the intrusiveness of a broadcast like this, which can invade the home and the ears of children, given that a warning at the start of the broadcast might not protect the captive audience. That may be true, but saying the broadcast has no social value is absurd: entertainment and humor are some of the most powerful social values.
Interestingly, during class discussion, the word that was most frequently voiced was "motherfucker."