I don't know if this counts and it's mild compared to some of you, but...
I think I told this story somewhere in more detail, but a bunch of us from college used to get together once a year and stay in a house. This is a pretty clean cut crew, no drinking or anything like that. 4 of us were in the living room sleeping, one woman on the couch, my wife and I on the floor, and another young lady beside me. In the morning the one on the couch got up and took a shower, and came back to the sofa, my wife got up to take a shower. The one on the sofa begins to masturbate and I watch in amazement. Obviously she thought I was still asleep. A few years when she got married, all I could think is, "I watched your wife masturbate."