It always used to make my laugh that Yoko Ono had made a film about her backside... in fact, I think she made a film called "bottoms", which was not specifically about anyone's backside. I found some info on it here and have quoted my favourite bit below:

Yoko on the Bottoms Concept:

"People's behinds have right and left and top and bottom. And each part moves separately. I thought it would be visually interesting to film close-up. Conventional movies have a background and part of the picture moves. In other words, there's always a stationary part in it. If you have close-ups of bottoms, the whole picture should move. Moreover, you can't control how your bottom moves, unlike your face, regardless of your intelligence. Cabinet ministers and laborers, beautiful women and ugly women are all equal when they take their clothes off. Their bottoms all have innocent looks beyond their control. I put an ad n the paper saying, 'Intelligent-looking bottoms wanted for filming. Possessors of unintelligent-looking ones need not apply.'