He Left Evidence Behind
Many years ago I owned a small neighborhood variety store. I worked most of the hours myself, but I had a few part-time employees. There was one guy who worked at night and he closed the store so I could get the evening off.
One morning when I came in to open the store I discovered in the rest room a soft porn magazine (we sold them in the store) along with a container of hand lotion on the sink next to a box of tissues. I realised he had obviously jerked himself off before going home and in a hast forgot to put away his 'supplies'. I never mentioned it to him but it made me realise that we all do it, but just don't talk about it.