Near the top of my list. Seen in a Hertfordshire pub toilet in the 1970s, when on a friend's stag night. I haven't seen it used elsewhere since. Although it no longer makes me chuckle out loud, it does still raise a smile and a fond remembrance. The helpful landlord had painted the brick walls white and outlined the mortar pointing in black to provide a 'built-in framing' for contributors. I can't now remember whether or not an indelible marker pen on a string had also been provided.
"Life is like a shit sandwich. The more bread you get, the less shit you eat."