A father-to-be fed a watermelon to a hungry hippo to reveal the sex of his child. The reveal happened Saturday at Capital of Texas Zoo in Cedar Creek. Blue Jell-O poured out of Tank the hippo’s mouth, indicating the couple is having a boy. But not everyone thinks getting the hippo involved was a good thing. “Worst gender reveal,” was one tweet. “That person's baby is not important enough to feed a hippo food coloring,” goes another comment.