This notice has been put up everywhere in Olympic Village. It is an inside joke for any foreigner who has ever been inside of a bathroom in Korea or had a local hock mucus at them.
Koreans are notorious for coughing (and sneezing) directly into the openings in your face. Basically you have an intimate moment with them because they share their bodily fluids into your nose, mouth, eyes and probably your ears. In the bathroom, the majority of Korean men and women will come out the stall, walk to the sink and spend many minutes fixing their hair and make up, then walk out. If they touch the water, it is to use it to fix their hair.
I wish I had money so I could put this notice on both sides of a heavy cotton shirt and sell it to foreigners. It would sell like hotcakes. Every foreigner would love to capture the irony of this notice. LOL. We are betting how fast the message will disappear once the Olympics end and international eyes are no longer on this country.