We played with chalk on the driveway the other day. The next morning we came out and found some tracks on the concrete.
We spent a few minutes looking at them and then Clover told me that Coffee (our imaginary cat) must have gotten out and made the tracks. She then spent five minutes calling Coffee as loud as she could. Before the neighbors came outside, wondering why someone was yelling about coffee, she came home.
Clover grabbed her and put her back in the house.
I think every now and then, even an imaginary animal has to get out and stretch their legs.