Invisible Animals

[At the end of storytime, going to sleep. Paul is still sitting up.]

Paul: I think I smell something.
Dad: You do?
P: I think it smells like wet dog. Only stronger.
D: I don't smell anything. Is it your blanket?
P: I think it is an invisible animal.
D: Really?
P: I know what it is. An invisible wet dog is walking down the street.
D: Oh.