Eat a bunch of crackers and whistle first.
A game for as many people as you would like. Divide the people into two or more groups. Line up in those groups. Hand out three soda crackers to each participant in each group. Explain that the goal is to be the first team to successfully eat their crackers and whistle as soon after chewing them as possible, beginning one person at a time per team. The first team to finish wins.