It's a play on the phrase 'shy and retiring', which is funny 'cause he isn't shy, and he's JUST announced he's retiring, etc. etc. The best jokes are the ones you have to explain!
Anyway, half an hour ago, Shia posted the following declaration of his intent to retire from public life on twitter. He mentions "attacks against his artistic integrity", which is interesting as no one forced him to plagerise Daniel Clowes' work in a short film, and then hire a plane to sky write an apology to him in the skies over LA. And then have a fight with Lena Dunham.
He'll find his self-imposed hermitage kind of difficult given he's got a war film due out with Brad Pitt that'll need promoting. Funnily enough, it's called Fury.