Proctor & Gamble has recently filed two trademark applications for "WTF" and "FML" - two colorful acronyms containing the word "F*CK". These marks would have formerly been rejected on the basis that they are "scandalous" or "immoral;" however, recent decisions validating registration of THE SLANTS (a band with Asian members) and REDSKINS (an NFL team) has changed the trademark landscape. A recent Federal Court decision noted, "the First Amendment protects private expression, even private expression which is offensive to a substantial composite of the general public,” holding that FUCT is a registerable trademark.
UPDATE
The U.S. Supreme Court has ruled that the USPTO's policy of rejecting "scandalous" marks is a violation of the First Amendment, making such trademark refusals an unconstitutional violation of free speech.