We use the term humiliation... but if what we are talking about is embarassment and extentions of being embarassed...

Think about the physical reactions we experience when we are embarassed. Face (and body) flushes, blood pressure and heart rate increase, the desire to be elsewhere (to run and hide, the flight part of the fight-or-flight response. )

Now, compare these physical reactions to what happens during sex... and the link between humiliation and arousal becomes clearer. It's just a different kind of foreplay that gets your blood rushing.