What Do You Dream About?

Today was Zander's 5th birthday, and we drive up to Ann Arbor and back for his party. Chloë slept both ways, for the most part. At one point on the highway driving back, she cooed for a moment, then said "a-da-da-da" and clapped three or four times... and then promptly fell asleep again. We figure she must have been dreaming, and we'd love to know what was so applause-worthy.