We were told specifically in our association that tongue rings, bellybutton rings, any jewelry is not allowed. Now checking for such things can be an interesting exercise. I would imagine I could get into more trouble checking for bellybutton rings as I would if my association found out a girl was wearing one and I didn't notice it. Can you imagine asking high school girls to pull up their shirts so I could check for a bellybutton ring? "But officer, my association told me to!".
