Italic sarcasm 

using caps or italics to indicate heavy sarcasm on instant messenger. When used in person, a high pitched voice and excessive head nodding is used to denote the intended italic sarcasm.

NcStateMark: Dude you're such a loser shutup.
Bosoxfanatic220: Mark. HAS FRIENDS.
NcStateMark: NOT RACIST.
Bosoxfanatci220: TALL.
NcStateMark: GOOD USE OF ITALIC SARCASM.

Italic sarcasm by Sawyer April 27, 2006

Italic sarcasm 

Italic sarcasm is saying a statement with a heavy sarcasm on words such as she, he, that, not and other major words (a higher pitched voice than usual is also necessary to get full effect). It is usually used to make fun of people, primarily in comebacks. When trying to use this style of speaking on aim, one usually puts the sarcastic word in italics or caps.

Sitting in Spanish class...

Mark: Hey Matt you suck at Spanish.
Matt: oh YOU'VE got friends.
Mark: NOT gay
Matt: BALLS

Observers: Wow, Matt and Mark having a pretty bad italic sarcasm fight.

Italic sarcasm by Sawyer Hicks April 9, 2006