YOMD is basically a lottery or sweepstakes. It is all random. You can enter by mail, or you are "automatically" entered by being in the parks. An accounting firm has randomly selected times and places throughout the parks where dreams will be handed out. Wearing shirts or standing out or having kids won't increase your chances. It's strictly a "right place, right time" thing.
Don't plan on winning anything, though. I wouldn't even plan on seeing anyone win. Some days we were at the parks we saw the fast passes or the bracelets for special extra magic hours and some days we didn't see any signs of anything.
