A couple weeks ago, Debbie posted about the difference between chimpanzee fear grimaces and chimpanzee smiles. This afternoon, Missy and Annie decided to demonstrate the many things that might elicit a smile, otherwise known as a play face.

For example, you might smile if your friend leaped out of the grass and tried to wrestle you to the ground.

Or, you might smile if you were the one doing the leaping.

You might smile if your friend was tickling your toes.

And you might smile if you tickled her right back.

You might smile if your friend chased you across a fire hose bridge.

You might also smile if you were the one doing the chasing. Especially if you went too fast…

…fell off…

…hung upside down…

…and kept right on chasing.

You might even walk away smiling after a move like that.