Balloon Race
Inflate several balloons before the cookout. Use a rope to mark a starting line and a finish line 30 feet apart. Have all the players line up on the starting line and give everyone a balloon. When you say, "Race," the players must place the balloon between their legs and race to the finish line. If a player pops his balloon, he is out of the game. If a player drops his balloon, he has to start over at the starting line. The first player to cross the finish line with the balloon between his knees wins the game. For a variation on this game, make it a relay race and play in teams.
Lawn Darts
Make a homemade game of lawn darts using beanbags and hula hoops. Scatter the hula hoops on the ground and write a point value in or on each hula hoop. Mark a standing line 15 feet from the closest hoop and have everyone stand at the line. Give each player six beanbags to try to toss into the hula hoops. Keep a record of each player's score, and the player with the highest score at the end of the game wins.
Shaving Cream Game
Try the shaving cream game for a messy water game. Divide the players into teams of five or six players. Designate one player from each team to get wet. Players who are going to get wet can stand on a line that is 6 feet from their teammates. Give each player a water gun. Take shaving cream and draw a heart of the same size of the front of each "designated wet player's" shirt. When you say, "Go," the teammates must use their water guns to wash the shaving cream heart off their teammate's shirt. Place a bucket of water for the players to refill their water guns if needed. The first team to wash the shaving cream completely off their teammate's shirt wins the game.
Ring Toss
Place 20 garden stakes in the ground and mark a starting line 10 feet away from the stakes. You can adjust the line closer or farther away depending on the ages of the players. Make rings using rope and duct tape. Have players stand at the line and try to toss the rings on the garden stakes. Give each player 10 rings to toss, and the player who rings the most garden stakes wins the game.