As director of communications at McDonalds, I suspect that Robert Gibbs has full and total access to the corporate twitter account and clears every tweet. My guess is that he thought he was on a private twitter (one of his own) and got drunk and posted this on the corporate account by accident.
As long as Robert Gibbs remains the head of communications for McDonalds, I would have to consider that that tweet is the official position of the company.
Bttt.
5.56mm