I was Order of the Arrow and a Life Scout, before I discovered girls and quit.
One summer at camp Tu-lakes (there was only one lake) we discovered that 'Off' worked kinda like invisible ink on tent canvas. We were writing all sorts of filthy words and phrases on our tent then watching them disappear.
It rained the day our parents came up to get us. The Off had disintigrated the waterproofing on the canvas. All of our artwork magically reappeared in the rain. That sucked.