That's Smart.

Jonah was playing on the beach.  Each time a boat passed, he waved and called out, "Hi, Boat!"  A few didn't take any notice (and probably couldn't hear even Jonah's high-decibel shout over the load motor) but finally one captain waved back.  Jonah pointed to the boat and told us very matter-of-factly, "that's smart."  Then he went back to digging.