George Mallory was a mountaineer who died in 1924, while trying to reach the top of Mount Everest. He's famous for an answer he gave to a reporter after being asked "Why do you want to climb Mt. Everest?". He said, "Because it's there".
So think about it. If you had a Sharpie or any ol' pen in your pocket and you came across one of these smiles, could you resist not interacting with it? Even if it is some cool, famous ball player that you might admire and respect, ...I mean, the guy is just giving you that big smile... how can you resist the temptation!!??
And then the next important question: Why is it funny? What exactly is this reaction us humans have, laughter, what the hell is that?? What is the origin of such a primal, uncontrollable reaction our body has to a simple silly thing like this? To me, that question is right up there with the meaning of love and life.