There may be a fairly significant cultural difference crossing the Atlantic on this one.  I've heard it described like this:  In the USA, you can talk about absolutely anything, sexual or otherwise, and can do it on network TV, but you can't use the words that most vividly describe what you're talking about.  In Britain, you can use all those words as freely as you like, but you can't actually talk about what they describe.

</semi-snarky stereotype>