A euphoric rush from playing video games, watching Star Trek, or any other activity typically considered "nerdy" which is comparable in intensity to an orgasm. The phrase "all over the place" can be added to the end to denote an even more intense feeling, though no bodily fluids are actually involved.
When I found out Leonard Nimoy would be playing future Spock in the new Star Trek movie, I practically nergasmed all over the place.
Derrives from the words "Nerd" and "Orgasm" use to describe a point of arousal from a nerdish event.
"Oh my god i made lvl 27 in my video game today!!" said John. " Don't have a Nergasm" said Jane.