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.
"This is so nasty it's awesome! I'm totally going to have a horrorgasm if the vampire tears out that dude's jugular!"
by gee's ghost September 15, 2006
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An event so scary you feel a strong sexual arousal afterward. These tend to be very strong and addictive.
"That new horror movie gave Jenny a wet and embarrassing horrorgasm"
by The Coin From Sonic March 29, 2017
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