When a character speaks no special action is taken. the player simply types and presses enter. When a player wants to speak as *themselves* rather than their character (Out Of Character), they will usually deploy an OOC fairy.
The defining feature of an OOC fairy is it's 'wings', or double-brackets. For instance...
In Character or IC (no 'wings'):
exampleChar: Hi everybody! What did I miss?
Out Of Character or OOC (with wings):
exampleChar: ((OMG sorry about that guys, the router threw a fit))
OOC fairies often appear with deformed or missing 'wings' due to typos. These poor creatures are treated with tenderness and pity by the entire community. stratosChatter/Morull is known to run a refuge for these unfortunate, malformed examples of the OOC fairy species.
Often the Memo becomes massively derailed by a solid mass of fairies. These 'fairy swarms' are considered a nuisance (dimensionallyStable/Anelie is in fact violently allergic to fairies), and some characters (notably motherfuckingHonkalicious/Gamzee) actively attempt to wave them away or disperse them with fly-swatters or cans of fairy repellent. It is unknown why some characters can see and interact with the fairies. Current wisdom puts it down to "motherfuckin' miracles" and leaves it at that. Nobody ever said these guys were genius scientists (although one or two definitely *are*).
variant; OOC brownies
When the roleplaying process suffers a critical failure and the characters simply stop doing *anything at all* while their players chat (often a result of a player's sudden and unexpected departure or a Full Henderson derailment) the entire Memo may be declared (or simply become) fully OOC, making the use of fairies redundant. wings are abandoned, although everything is still considered OOC, and the resulting posts are considered OOC brownies (fairies without wings, geddit?)