If it's not for sale, it's free.

(As we are driving past Butler University)

Noelle:   I think that's free mulch.
Phil:   That giant pile of it there?
Noelle:   Yea.
Phil:  What makes you think it's free?
Noelle:   There's no sign saying it's for sale, so it must be free.
Phil:  Of course! (As we then pass a preschool playground) Hey look at all those free babies!  And look -- a free dog and jogger!
Noelle:  Shuddup.
Phil:  Free airplane!  Free fire trucks and ambulances.
Noelle:  Pull over.
Phil:  I'm sorry I'll stop.
Noelle:  No pull over for the ambulance.
Phil:  Oh right.