It has to do with the icing on this optical illusion cake. The question is what color is it?
If you keep looking at it, it changes colors depending on which angle you view it from. A 30 second clip was uploaded on YouTube by Charlotte-Sometime, who appears to be a cake decorator.
It shows a spinning cake that changes from yellow, orange, and pink to green, blue, and purple.
It is "the dress" of the pastry world.
VIDEO: What color is this dress? Join the debate!