Voulez Vous Cliche Avec Moi?

On a college campus, colored chalk on concrete is a popular communication medium. This morning I saw this written on in chalk on a step riser:VOTE LIKE YOU MEAN ITThat had to be the Campus Democrats at work. But what does it mean, exactly? If I vote like I don't mean it, my vote won't count? If I do mean it, my vote will count extra? If I'm not serious about voting, the terrorists have won?