The Account Smurf's Sister has been using since 2004. 
Nobody can ever spell her name right. Ever.
If the moon was made of babies, she'd eat it.
Her topics boast an abnormally long existance, unless someone posts them all on Snack Attack afterwhich a mod locks most of the topics.
Claims to be a girl. Also claims there's no such thing as girls on the internet.
She loves pictures of people with monocles, and thinks everyone else should too -- because really, monocles are awesome.
Only two things can survive a nuclear holocaust: cockroaches, and topics made by Pleinair.
On January 29th, 2007, the user and Pleinair topic hater GanonNess attempted to hijack one of Pleinair's topics by flooding it with posts. It got to 200 posts before he was warned. Should he have succeeded [this is in need of an edit, his work went noticed as Sine locked EACH AND EVERY Pleinair topic up until that point. Fix this.] he would have sent a link to the locked topic and threatened to do the same thing to every other topic, one topic a day.
To summarize: Pleinair is a defining denezin of board 8. It's generally impossible to engage Pleinair in a normal human conversation on any topic- the one and only activity Pleinair engages in on the board is bumping topics with one-liners relating the obscure oddity the topic is about.