"I like to think that the Riddler received his latte with just a circle of milk foam on top of his latte and then drew the question mark himself, perhaps with a spoon or utensil," barista Morgan ...

The Riddler Grafitti As (again needlessly) revealed in the trailers, the sequence that sees Batman preparing to fight Superman and stab him with the Kryptonite spear has a Riddler question mark in ...

Since the question mark is of a darker color and placed within a circle of milk foam, it would have had to be hand-drawn on top of the milk foam after adding it to the latte.