*A four person water ballon launcher.
*A "potato gun"- made by my nephew when he was in junior high. PVC pipe, hairspray, a Bic lighter and a 10 lb bag of potatoes. The goal- see if you can shoot a potato across the lake. Don't try this yourself- I'm not even sure that it is legal, but it was fun.
By the way, the nephew that made the gun is now an aerospace engineer. Maybe it is ok to let some of your kids play with fire.
*An eight year old nephew willing to retrieve potatoes that didn't disintegrate or make it into the lake. BONUS: Even though he's from Minnesota, he's wearing the KU Jayhawk t-shirt he got from his aunt and uncle in Kansas.