It's been quite a while since I made a post in this genre:
The above photograph comes a series of shots showing scenes from the back alleys of Shanghai. The sign says:
zài cǐ dàxiǎo biàn 在此大小便 (whoever urinates or defecates here)
jiārén sǐ guāngguāng 家人死光光 (your entire family will die)
zhū gǒu bùrú 猪狗不如 (you are not equal to a pig or a dog)
For another colorful sign of this sort on the side of a building, see "Urination is inhuman", which has a list of earlier "lesser convenience" posts at the end.