The first time I've seen something like this - was in Kawagoe.
It says "Do not pee or poo here" and presume that previously people have been dumping their goods in the area.
Japanese Public Toilets
Which reminds me of an important topic - public toilets. Public toilets turn out to be quite smelly over here - the pee and poo vomit inducing smell assaults you when you walk in to some of the toilets. Some of the worst ones I've been to are in Shinjuku.
Many public toilets don't have paper and instead have a vending machine outside selling "chirigami" - paper to wipe your bottom. Public toilets over here commonly don't have towels to wipe your hands either.
The worst thing about Japanese toilets are the Japanese style hole-in-the-floor toilets where the previous person missed and left their goods on the floor for you to look at and enjoy.
Did you find the toilets clean or dirty when you visited Japan? How about the public toilets in your region - clean enough to eat your dinner off the floor or vomit city?
Hmmm.I feel sick after writing all that ^^;