Used commonly by MMORPG players to convey that they are unimpressed or annoyed to the point that they actually type it out.
Usually the player is trying to show that they clearly know more about a video game and are mocking other peoples knowledge of said game.

Unfortunately it's just a fucking game and knowing more about interactive fiction than having social/survival skills classifies the player as a total douchebag and most likely to be the first to die when presented with a life or death situation.

a noise of exasperation when the world is getting too hectic.

1. To show exasperation, of course.

2. A sign of infatuation in girls

A universal response to any given emotion.

Ridiculously talented black metal band from Japan.

a noise a girl makes when a boy prematurely ejaculates under less than 3 minutes during sex

Depressed, lonely, sad.