Many years ago, I did this object lesson for our YW. I put a purse in the room that the girls knew belonged to one of the YW.
This "designated" YW left the room. After she left, I opened it up and asked them who wanted what.
If the girls didn't speak up for it, I would just give it out. "Here, you can have this gum." "Do you want her lipgloss?" etc. The girls were shocked. Then I told them just as you wouldn't give away your friend's belongings, you should not give away your friends' secrets...
1 Timothy 5:13: " And withal they learn to be idle, wandering about from house to house; and not only idle, but tattlers also and busybodies, speaking things which they ought not."