yea here in my location its normal for children of all ages to play show me yours and Ill show you mine games. some are like what you posted others are things like spin the bottle (everyone in the game sits in a circle and spins a bottle. who ever the bottle stops spinning at has to show something either in front of everyone or privately to the spinner. other variations of this game include mild touching or kissing depending upon the age of the children and their mentality of this game) whistle stop (two people one shows and stops when the other whistles, or one touches starting out with normal touch and then moving into the gray and do not touch areas and the one being touched whistles when they want the other to stop)

my point I can name many show me yours and Ill show you mine games that on between children of all ages.

do I think this situation in the posters post was handled right...if in my location this is exactly how it would have been handled.

unfortunately theres no way to keep children from each other in situations like camp or school unless the poster removes their own child from camp and school. but you can ask that better supervision is done so that the children in question are always in the presence of an adult who can ensure private show me yours and Ill show you mine situations at camp cant happen again.