Someone on HitTail.com has been searching using the phrase postile definition.
I can’t find a definition of this word on any dictionary, although on an entry on MySpace.com someone said they were going to go ‘postile when icu.’
Maybe postile is a new word, a slang word that hasn’t yet made the dictionaries. I’ll have to keep an eye on it in case it comes in handy. (Although I can’t see it outdoing skew-whiff for the time being. I’ll go skew-whiff when icu? Maybe I will.)