As a kid, I somehow got it into my head that the proper way to enjoy a Blizzard from Dairy Queen was to try and drink it like a milkshake. Doing this made the straw collapse in on itself and when anything did get through, it was — if course — melted and less than satisfying.
However, the fact that this even kind of worked compelled me to try it multiple times until I finally started using the spoon they provided. I was a determined child, if not a very practical one.
So it hardly came as a surprise to me when people got a similar impression from the unusually-shaped spoons that McDonald's uses for their McFlurries. And as far as we can tell from a new promotion, it's not news to them either.