Four!

The world changes when you turn four.  Mysteries that befuddled you before fall open before your eyes.  You are older, wiser, and more mature.  Even the most fundamental things change.  Instead of going when the countdown reaches 3 (as in 1, 2, 3!) Isaac now goes on 4.  It just happened one day.  Instead of 3, it was 4 that mattered.  Over the four weeks or so, it has been shortened to simply: "4!"

Here is a video example.  Note right before he breaks the sticks he shouts out "4!"  Its been that way for a month now and it is still hilarious each time he does it.