This application actually works - if you use it in the night, the fact that you actually see that result influences your mood so that the next morning you actually feel that way.
It's a very fun game to use around girls - the various answers like
"You will feel sexy tomorrow" or
"Tomorrow will be a sad day" is very convincing among the people I play it with.
My friend Serena loves this game and uses it on all her friends. Try it!