What makes the Buddha laugh?

An indicator of spiritual maturity is a rising above the ego and seeing beyond the mistakes of our brothers and sisters to their oneness with us in God's creation. This seeing beyond is what some call "forgiveness." In simpler, more vulgar language, it is overlooking the bull shit and side stepping the drama.

People are more than their problems and often they can't see that, but we that can have a role to play in gently laughing at the absurdity. When our brothers and sisters can laugh along with us we have joined with them in what A Course In Miracles calls a "Holy Relationship."

Why is the Buddha sometimes depicted as smiling? What is the Buddha amused by. What makes him laugh?