First click "Go!". *don't click any of the party hats before clicking "Go!" nor while the party hats are moving* Then as the party hats move, keep an eye on the party hat with the ball underneath it. When the party hats stop, click on the one you think has the ball underneath it. If you're right you can win or advance to the next level. It's your choice. If you're wrong you lose. Enjoy!
