For Europeans, it’s always difficult to understand some moral ethics in the U.S. To cut a long story short: violence is OK, naked skin (or even worse…) is bad!
When going to the movies last week I saw the rating for Live Free or Die Hard ("Die Hard 4.0" for you Europeans) — "PG-13 for intense sequences of violence and action, language and a brief sexual situation" (in Germany, the movie is rated "16", so no one under the age of 16 is allowed to go see it in the theaters). Knocked Up on the other side (that movie shows some… naked skin… but not more than you can see all day in these pr0n-alike music clips on MTV) is "rated R for sexual content, drug use and language" — in Germany, you can watch it if you’re 12 years or older.
For further information, see an explanation of the movie ratings on the MPAA website.
And to make things worse, today I was sent two links to an article from the German Spiegel news magazine and one on Boing Boing — male genitalia either in 0.5 millimeter size (that’s 0.019685 inch) in an illustration of a museum scene in a children’s book or in the form of concrete phalli (formerly known as "cement posts") are terrorizing the U.S.! As if there weren’t more… serious… problems…