Man, other than a few other people on this board, I feel like a bit of an oddball. With any luck this won't be the object of, "Teeheehee, this guy is a wierdo/voyeur."
Anyway, I think the hottest thing in the world, is to catch a girl jilling and watch her without you knowing. Now, my wife knows this so she has indulged me from time to time, but it isn't as good as when they have no idea you saw. Don't get me wrong, it is still awesometastic.
The sad part of the story, it has only happened a handful of times since we met 8 years ago. Here is how it went the first time. I had gone to bed and to sleep quite some time before my wifey and didn't awake when she came to bed. [sidenote-admit it, sometimes you don't want sex, you just want to rub one out to go to sleep. Ladies too. So, I didn't think she should have woken me up.]
Well, I woke up a little while later, thought she was asleep, and in a just awoken foggy thought process, discovered that something strange was going on. I kept my silence and reallized. HOLY CRAP!!! The bed shook with voracity and there were quiet but restrained exhalations. It was probably the single most sexy thing I've ever witnessed(which includes seeing her lick another hotties middle third).
The next morning, just to verify, like an idiot, I asked. After some denial and embarassment, she finally admitted it. It wasn't until months later without a similar incident that I realized the confrontation was SO SO stupid of me.