This happened twice at the lake front in milwaukee. First time I was with my fiance and we saw some older guy with his shorts rolled up. It looked like he was wearing a diaper and was creeping other people out. I thought it was funny but creepy, he was staring at me and my fiance.
The following year, my friend and his wife, my fiance and I all went to the lake front in milwaukee and again I saw the same older guy doing the same thing. All four of us were giggling and its weird. I think this older guy gets a rush doing this.