How many porta-potties were needed for about 30,000 runners at the 2013 Beijing Marathon? A new photo from this year's Beijing Marathon showing athletes peeing in the open with a female runner in the lineup has gone viral .

Year after year there has never been enough porta-potties along the route of the Beijing Marathon. Many runners have been forced to "go" in the open, especially at a section of the red walls right outside the Forbidden City. It is even claimed that many athletes would deliberately pee there for fun just for the "tradition" to wet the red walls and flood Beijing.

Whatever the reason, the practice has resulted in a river of pee and viral photos, include one where a female runner is seen squatting among the standing men.