These famous hippos, stars of the wild Hippos Go Berserk book, have been partying nonstop since 1977. Surprisingly, it hasn’t aged them a bit—they are as enthusiastic and unruly as ever. And now it gets even berserker: hippos have overflowed the book, invited more hippos, and now star in their very own puzzle. The way they explain it is this: It’s their job to go berserk. It’s your job to try to restore order. Good luck with that.