I've been on the "peeking" end before. I had this good friend who I saw once, briefly, in a public shower and I almost dropped dead at the sight of it. After that, I always wanted to get a better look at it. We were close enough that I felt comfortable asking to see it, and I did... well, he got really freaked out. And no, he never showed it to me. lol. That was four years ago.
He knew I was going through a really weird time, psychologically, so I think that made things twice as awkward for him.