1. Tickle him.
I was trying to see his teeth by tickling him, but it didn't work. Seeing/hearing him laugh makes me smile though.
2. Let him watch T.V.
Ethan was laying on the floor and I had the TV on but wasn't paying attention to it and then he started laughing so I had to see what he found so funny. I rewinded it two times and he still laughed at it.
It was a movie called, "The Secret Life of Walter Mitty." It was made in 1947 and is about a daydreamer that sees himself as a sea captain, surgeon, RAF pilot, and other heroes with a blonde. The guy is kinda silly...watch for yourself.