An awful disability many people are afflicted with. Someone who is completely normal in everyday life, if given access to the internet, will turn into a complete jackass. The person begins to spurt racial slurs, random insults (mothers and sexual orientations are favorites), radical views and opinions and just various garbage.
These people afflicted with the disease are often called "Trolls".
Examples of Internet Turrets
Everyday Bob: Yes, I did vote for Obama.
Internet Bob: Fuck no, i didn't vote in that bitchass communist porch monkey! However, I did fuck his wife!
Everyday Bob: That girl is very appealing to the eye!
Internet Bob: *fap*fap*fap*
Everday Bob: That's an interesting point of view.
Interent Bob: Fuck you, you commie homo!
Everyday Bob: *joining in an engaging conversation, and staying on topic*
Internet Bob: Who else wants to have intercourse with Jessica Biel.