When something is so
disgusting that you gain sick pleasure from it or get turned on because it's just so gross.
Like when the perky cheerleader in the horror film gets her head
chopped in half and blood and gore squirts everywhere, and you feel that rush-type-thing as you scream. Or when you're reading a really terrifying story and you're like squirming around in
anticipation of what happens next and all giddy and scared.
Basically getting excited by something creepy.