Figure out the language
There is one counselor who has several sticks. They make up a random combination with the sticks and say, “This is a secret language; the sticks spell out a number 1-10, and 1-10 only.”
You can make as many stick figures and arrangments as you want, it doesn’t matter. As long has you are making numbers with your hands. Say it is a 5, all you have to do is put your hand on the ground and spread out your finger.
The fingers that you make numbers with must be on the ground and visible, all the campers are looking at is are the sticks.
If your campers can’t get it, tell a few other counselors the secret and have them guess. This drives campers crazy that a counselor can figure it out.