If you're looking for a game to foster carnival-like conviviality, try playing lucky duck. This game of chance takes only a few minutes to set up in the backyard and offers a bright diversion for all ages.
Fill a plastic wading pool with water, then add the main attractions: 24 to 48 rubber duckies. The only "technical" thing you need to do is to paint the underside of one duck red (or another color) with a waterproof paint to set it apart from the others; this duck will be the "winning" duck. Of course, this paint job will not be visible when the ducks are upright. You could also just use a colored marker.
To play, participants choose a duck at random from all the floating ducks. The player who selects the duck with the painted underside will be the winner of a small prize or bragging rights. If the player don't pick the right duck, he or she puts it back and then another player tries to pick it [source: Freedman, Carnival Savers].
Variations include having players find two painted ducks to win or writing a number under each duck. Different numbers correspond to different prizes.