A) Term used mostly in a derogative way towards someone that radiates nerd.
One who probably:
1. is into anime
2. likes a lot of sci-fi
3. plays World of Warcraft or Dungeons & Dragons on a day-to-day basis
4. goes cosplaying
5. has more than four (4) gaming systems, some of which are not even manufactured anymore
6. trading cards?
Nerdbag 1: Guys, get ready to attack. Everyone got their special abilities macro'd to their keyboards?
Nerdbag 2: Hold on, I'm out of manna.
Nerdbag 3: Goddamn it!