Crazy Cat appears briefly, for only a few pages, but it's still a potent symbol in Mockingjay. Crazy Cat is a game Katniss plays with her family's cat Buttercup in District 13. She waves a flashlight around and he goes bonkers, chasing the light. (Maybe you've done this with your own cat and a laser pointer. We sure have. Good times.) Buttercup is most interested in the light when he can't get it but if they play the Crazy Cat game for too long, Buttercup really goes bananas.
One night Katniss realizes that Crazy Cat is a metaphor for how the Capitol plays games with her. She compares herself to Buttercup and the light to the imprisoned Peeta, who she wants desperately, but the Capitol dangles out of reach.