While you come in a rush, when you leave please flush
There has been a big push in the last decade in China to get people to make simple adjustments in their day to day life that will greatly improve public health. Don't spit in public. Don't litter. Wash your hands. The fun thing about these campaigns is that the Chinese like to play on homonyms. The image above, stuck to the wall in the back of a bathroom stall, reads:
"Lai Ye Chongchong, Qu Qing Chongchong"
In this case, the focus is on the word "chong", which here means "to be in a rush" and "to flush the toilet". (This campaign is brought to you by "Comfortable Rectum, healing hemorroids with a patch you stick on your belly button.")
In chinese, the number of sounds are far more limited than in English. In order to have a rich and articulate language, they relay on 4 tones so that the sound "chong" for instance, can be pronounce with 1 of 4 tones. However, even within the same sounds with the same tone, there are numerous meanings which can only be clarified by reading the character. It all makes for a very challenging language for an American to study, but a fun and subtle language with numerous levels that the Chinese enjoy.