Sometimes we smile to hide a tear
Sometimes we laugh not to show fear
Sometimes we smile to make people not see
How unhappy we really can be
Sometimes we smile to hide our true intentions
Sometimes we send people through in the wrong direction
When we fake our smiles we lie to ourselves
No one can see we are calling for help
Sometimes we smile to make people feel better
Sometimes we smile but are always under the weather
Sometimes we cry through our hidden smiles
No one sees our inner child.
Sometimes we smile but want to cry
Fake smiles aren’t worth the while.

Poem by [link]

As you can see, it applies to the image nicely.
One can smile, one can seem happy, but not really be happy. One can have a fake smile, just like this guy does. (: