In mainland China and elsewhere, the squat toilet is the norm. For those not familiar with the squat toilet, it is a flushing ceramic toilet bowl, but it is recessed into the floor. There is no seat, and like the name implies, you squat to use it. Those who are used to using a squat toilet get confused on how to manage a western or "normal" toilet, and sometimes stand on the toilet seat. I have seen footprints on toilet seats in Hong Kong, but I never saw a sign like this one until now. It was on back of the stall door.