As the late 60's and beyond movies got more daring, stars you never thought would've taken it off, did.
Here's some that have bared something or another that I would've never expected:
Jack Lemmon (along with Juliet Mills) in Avanti
Burgess Meredith in Such Good Friends (never seen it, just heard about it)
Julie Andrews in SOB, actually this did get a bit of publicity at the time
Sir John Gielgud in Prospero's Books
what are some surprises you have come across?