When someone has a fit
(Squealing, Giggles, Kicking of Feet and Legs, Jumps of Joy, etc)
over something they are very passionate about.
Dude 1- "Dude, did you give your hot employee those sick-ass shot glasses for Christmas?"
Dude 2- "Yeah, brah. She had a total fucking Nerd Seizure when I gave it to her, I think I totally scored."