Batman smiles when he meets his (co)maker

Natalie's response: "Because he's being introduced."

Golden Age Batman smiled all the time

Natalie's response: "Because they're taking a picture."

When under the influence of Scarecrow's toxins...

...Batman smiles a LOT!

From Batman 571

Natalie's response:   "It's just a drawing!"

Robin's jokes make Batman smile...

...unless this is more of a 'smirk.'

Natalie's response:   "That's a mad smile."

Batman Smiles in the FUTURE!

Superman made a funny.

via Siskoid's Blog of Geekery

Natalie's response:  "He's making fun of Superman's white hair."