There's a village in which a Zen Master and a little boy and on his 14th birthday he gets a horse...and everyone in the village says "How wonderful, the boy got a horse!", and the Zen Master says "We'll see."

 Two years later, the boy falls off the horse and breaks his leg.  Everyone in the village says "How terrible!" and the Zen Master says "We'll see."

Then a war breaks out and all the young men have to go off and fight...except the boy can't because his legs are all messed up and everyone in the village says "How wonderful for you!" and the Zen Master says...

 and so on and so forth.

(Source: Charlie Wilson's War, 2007)

The Law of Unintended Consequences: "Whatever you do or don't do, regardless of whether it has the effect that you wanted, there will be at least three other consequences that occur that you didn't intend, at least one of which is usually unpleasant."  What have you done TODAY that might have Unintended Consequences...?