我看主要還是和人自己有關。有誰會在熱鬧的大街上方便呢？^_^

應該與缺少廁所有關吧？

另外，“DO NOT PEE HERE！We pee back.”

指的是一種能反射小便的牆，高科技啊：

https://www.entrepreneur.com/article/249023

San Francisco’s Department of Public Works is combatting the disgusting problem of tinkling in public with a completely off-the-wall solution -- walls that “pee” back on the jerks who pee on them.