The pleasure some people get when they are propostioned at the gym (after having strutted and flirted shamelessly) and coldly looking the poor slob in the eye and telling them "no" and laughing at them and making them want to crawl inot a corner and die.
or
The pleasure one gets from telling a big, over-confident gym jock "no" when he starts hitting on you in the gym.
The actual meaning of gymnophoria is actually something which happens to me all too often when I walk to into a room full of ladies: The sensation that someone is mentally undressing you.