Very interesting (at least to me) article from last year by Steven Pinker in The New Republic (if the sight of curse words offends you, do NOT read on):
Fucking became the subject of congressional debate in 2003, after NBC broadcast the Golden Globe Awards. Bono, lead singer of the mega-band U2, was accepting a prize on behalf of the group and in his euphoria exclaimed, “This is really, really, fucking brilliant” on the air. The Federal Communications Commission (FCC), which is charged with monitoring the nation’s airwaves for indecency, decided somewhat surprisingly not to sanction the network for failing to bleep out the word. Explaining its decision, the FCC noted that its guidelines define “indecency” as “material that describes or depicts sexual or excretory organs or activities” and Bono had used fucking as “an adjective or expletive to emphasize an exclamation.”
Cultural conservatives were outraged. California Representative Doug Ose tried to close the loophole in the FCC’s regulations with the filthiest piece of legislation ever considered by Congress…
…The Clean Airwaves Act assumed that fucking is a participial adjective. But this is not correct. With a true adjective like lazy, you can alternate between Drown the lazy cat and Drown the cat which is lazy. But Drown the fucking cat is certainly not interchangeable with Drown the cat which is fucking.
If the fucking in fucking brilliant is to be assigned a traditional part of speech, it would be adverb, because it modifies an adjective and only adverbs can do that, as in truly bad, very nice, and really big. Yet “adverb” is the one grammatical category that Ose forgot to include in his list! As it happens, most expletives aren’t genuine adverbs, either. One study notes that, while you can say That’s too fucking bad, you can’t say That’s too very bad. Also, as linguist Geoffrey Nunberg pointed out, while you can imagine the dialogue How brilliant was it? Very, you would never hear the dialogue How brilliant was it? Fucking.
More here.