The shake is a layered blueberry shake topped with whipped cream, rainbow sprinkles, and a upside down sugar cone as a "horn."
With unicorn-themed cereals, cupcakes, and drinks appearing in recent years, it was really only a matter of time before major fast food chains got in on the action. Surprisingly, it didn't happen in the US first (although maybe it's because Burger King doesn't carry sugar cones here).
Photo via Burger King.