Term used to describe extreme anger, offence, indignation, and other similar emotions by a nerd, geek or similar. Nerd Rage can be triggered by a number of things, most commonly through helplessness in the face of bullying, internet fights, or seeing their favorite film/show/anime/etc degraded or insulted in some way.
"So, did you see the new Transformers movie?"
"Yea. Michael Bay screwed it up so badly, it set my Nerd Rage off big-time."