Possum

We were coming home from Mom's tonight and Zander was very quiet in the backseat. The conversation went something like this;
Mom:  Zander are you asleep?
Mom: Zander are you asleep? Waits for a few seconds.
Mom: Zander are you playing possum? (Still no response)

After a minute or so, Zander said, "I am not asleep, I was ignoring you."
Mom: Oh, that is why I asked you if you were playing possum, that is what they do."
Zander: Really, they ignor their moms too?
Mom: No, (laughter) they pretend to be asleep or dead.
Zander: Oh.