McDonald's: What is a Flat White?

McDonald's have recently introduced the Flat White to their McCafé menu with an ad that aims to tackle the mystery of a Flat White. 

The reason I think McDonald's have succeeded with their 'What is a Flat White' ad is they have successfully played on the recent coffee phenomenon to mock hipsters and trendy coffee shops.

I really like brands who have a sense of humor and ultimately make me laugh. Clearly the flat white is something of anomaly in Irish/Western society.