It's tuff to decide, so many good options, but I had to go with Humiliation. It's one of those things you just can't describe, normally it conjures up a really crappy feeling, but for some reason when it's tied to a sexual responce it's incredible. Almost feels like it's magnifing everything your feeling, every little touch, or wiggle, or gust of wind. Makes you want to just die, or orgasm right there, but you can't decide which.

It may have to do with the nature of humiliation, being that it's already a situation out of your control it can invoke the feeling of bondage even if you aren't tied in any way ((but it's even better when you are!))

To date the most incedible thing I had happen was when one of my friends ((he shall remain nameless )) thought I was being just a little bit too bitchy one day and spanked me in the parking lot outside his store. My face was about as red as my ass, and it wasn't all from the tears.