About

The NO U image is a sarcastic way of pointing out that the Original Poster's [OP] comments apply more to himself and is therefore an idiot. It is also an effective method of trolling a troll (which goes hand in hand with the former sentence).

Orgin

This meme originated on the Something Awful forums where epix flame wars would often erupt. Eventually the arguments became so illogical and the insults so repetitive that often it needed to be pointed out that the OP was being a hypocrite.

Background

NO U harkens back to simpler days when we as children would engage in what were to be the precursors to forum wars. Arguments over common issues would devolve into anarchy as neither party was willing to concede their point. This inevitably led to attacks on character which subsequently devolved into childish name calling which of course would usually finish with NO YOU.

Usage

In popular forums where any user can login and express any opinion, NO U become a more prevalent meme. Because of the nature of forums and how they do not really offer a good solution to ignoring trolls (or otherwise inappropriate comments) NO U becomes a simple and effective way of pointing out that the OP's comments are in fact more aptly applied to himself than his subject. Furthermore, as trolls typically thrive on eliciting a an emotion reaction from those they've frustrated, the NO U retort shuts down their initiative and unofficially labels them a troll, without using more than 3 letters. The brevity in the response further exacerbates the troll's motivation from pushing further.