When LJ mentioned "wrong door" antics, it reminded me of something funny (from anyone's perspective but mine...)
The first and only time I attempted wrong door interaction, my boyfriend and I were in the shower, standing. It was not pleasant, and was in fact extremely the opposite, but I put up with it for a few minutes because, hey, I like doing stuff for other people. But after awhile I just couldn't take it, so we stopped.
Months later we were talking about our "firsts," and how old we were when they happened. I mentioned that he had been my first guest in the wrong door, and he was totally caught off guard--not by HIS recollection he wasn't. I reminded him of the time, and he remembered being there and all--BUT HE HAD HAD NO IDEA AT THE TIME that he was in that particular orifice. He'd thought at the time I wanted to stop just because, or we were running late, something.
So I endured quite a lot of pain purely for his pleasure, and he wasn't even aware enough to appreciate it.