Are you looking for a fun game to play that will keep the kids busy? These Balloon Cup Shooters are awesome! And they will definitely keep the kiddos entertained for a few hours. All you need are plastic cups, balloons, duct tape and ping pong balls.
Balloon Rockets - I've done this in several science camps I've conducted. Kids have fun with it. But, when the balloon deflates it may fall off the straw because it's surface area changes - another good thing to show and explain to kids.
Marshmallow Shooters DIY Kids Craft - Coffee Cups and Crayons DIY Marshmallow Shooters! Such a fun craft for kids to make and play with! If you love arts and crafts an individual will really like this cool website!
32 Fun DIY Backyard Games To Play (for kids & adults!)
Paper plates, Popsicle sticks, and a balloon are all you need to play Balloon Ping-Pong. (Not sure how sturdy the paper plates would be, but may be able to do something similar for a carnival/game night social event theme.