Reference to The Phantom of The Opera a Broadway musical by Andrew Lloyd Webber, also a movie. This refers to whenever Erik is touched by Christine and kind of freaks out. A play on the word orgasm.
Christine touched her hand to Erik's face and he had a Phantomgasm.
A desription on the climax of visual excitement, characterized by feelings of pleasure and awe, accompanied by a smile or exclamation, when viewing a photograph.
Person 1: Whoa...WHAT!
Person 2: Did you just have a photorgasm?
Person 3: Haha! Yeah.