It's vintage Vivienne Westwood, dahling, but that doesn't make it OK. That's his missus, which would explain why she let him out in it.
Needless to say his mountie hat spawned it's own twitter handle (@pharrellhat) and a number of tweets along the lines of "Pharrell is incubating a fetus in his brain" from @samir, and this little gem from @TerezOwens
Neil Patrick Harris also got involved. Of course he did, he's aces.
People Magazine held the following pole which they published via Instagram
Other folk on Twitter, Instagram and Tumblr compared him to Smokey The Bear, The Hogwarts sorting hat, and one of the lesser known Pokemon, Diglett.
@GwynneMims via Twitter
Then the good people at Buzzfeed broached the subject of what he may be storing under the hat...
I reckon it was a simple matter of him trying to keep up with Daft Punk. Well, he was due to perform onstage with them. It's obviously Pharrell's interpretation of a giant helmet... See Daft Punk, Nile Rodgers, another one of Pharrell's hat and Stevie Wonder's performance from last night below. Feel free to wriggle out a jig in your office chair - it'll be hard not to.