Tenacious D perform You're the One That I Want (the song from the movie Grease) with Andy Serkis, the voice of Sm éagol from Lord of the Rings. Filmed December 2004 in Wellington, New Zealand. In a word: hilarious! Gollum dropping a couple F-bombs with The D couldn't be anything less.

http://www.youtube.com/watch?v=dG2FzHjzJj8