I love you, my sweet hungry bear

We have recently been treated to larger and larger glimpses of Xander's emerging sense of humor. His favorite game lately is to ask me to sit down next to him and read him a storybook. Moments into the story, he will surprise me by turning to me, raising his hands like claws, and roaring like a hungry bear. My part in this game is to spring up terrified from the chair, run around behind the chair and hide, peeking cautiously out after a moment to see if the coast is clear. At this point, Xander will say, "Mama? Mama?" in a neutral tone of voice, pat the chair next to him, and give me a look like I'm crazy. Then back to the beginning. He finds this endlessly hilarious.