Water balloon volleyball is really fun. A few years ago at a reunion we did a pie eating contest with graham cracker crusts, a big can of chocolate pudding, and spray on whipped topping. We had a few different catagories of ages, and then after the big dinner that night we had the finals. It was really fun. Also a hot dog eating contest would be fun.
Cheeto head is great. Buy some shower caps, several bags of cheap cheetos, like at the dollar store, and a few cans of shaving cream. Divide your group into teams, tell them that they need one catcher, and the rest of the team are throwers. After the catchers have been picked, ask them to sit on chairs at the front of the group. Pace off about 10 feet from the catchers and make a tape line that cannot be crossed byt the throwers. Ask each catcher to place a show cap on their head, cover the caps with shaving cream, pour out a big pile of cheetos in front of each team, and give them 2 minutes to get as many cheetos to stick on onto the head of the catcher as they can. Ask someone in your family to be the judge. This game is a scream!
"Whether you believe you can or believe you can't, either way you are right."