Naked movie/tv extra

Has anyone appeared nude as en extra in a movie or tv show?
How was your experience, and how did you get into it?

Its something on my to-do list as long as I can remember, I know sometimes naturists organizations/clubs get approached looking for volunteers/participants, and other times casting agencies put out notices, if anyone knows a good agency or website to keep an eye out for UK and Ireland based productions please let me know!