Someone who has no idea how to use the English language, yet insists on spreading his/her own horribly distorted version around the 'net, unaware or uncaring that they are demonstrating to the world just how stupid they are.
Individual #1: "Dude, you're so gullable. I wan2 kil u."
A particular variety of spidiot who insists on submitting offensive, mis-spelled, innacurate or obscenity-riddled entries to UrbanDictionary.com under the false impression that this somehow makes them funny.
"There are far too many urban dicks around this site."
One with far-more-than-average knowledge of a subject, such that said subject becomes the ruling force of their life, resulting in a heavily depleted set of social skills; despised and/or pitied by geeks and norms alike.
Typically applied to computers, though any subject is viable for nerd-dom.
"Enjoy the dance. The wall of the nerds is at the back."