Sack racing is one of the most popular picnic party activities in the world! It's really fun to participate, really fun to watch and really fun to organize.
You'll need to get a bunch of empty potato bags. Make sure they are not plastic bags, because they will tear up and get destroyed before the race even really starts. You should be able to get proper potato bags at a local farmer or maybe a home depot store.
Once you got the bags, you should set up a fun course. You need to set up at least a starting point and a finish line, but you can also add obstacles, twists and turns in between.
All the participants climb into their sacks. When the race starts they have to jump in their bags from start to finish, without climbing out.
Whoever crosses the finish line first is the winner!