Tongzi Dan or Boy Eggs, are urine-soaked hard-boiled eggs that straddle a line somewhere between local tradition and modern medicine. Although the concept is off-putting at first, the eggs have been standard street fare in Dongyang in Zhejiang Province for hundreds of years.

The process for making Tongzi Dan is similar to making other types of boiled eggs, such as tea eggs. Just instead of tea or water, the eggs are soaked in urine. After being brought to a boil in the steaming urine, the eggs are removed, their shells are cracked and they are placed back into the boiling urine to soak up flavor. Residents of Dongyang have described the powerful smell of the process as both rejuvenating and completely disgusting.

Most people in Dongyang fall into one of those camps, either swearing by the unmatched taste of the egg, or staying fifty feet away from the vendors. Besides the taste, many people attest to the medicinal properties of the eggs as well, stating that they increase blood flow and lower internal temperature. While historical studies show that this may hold some weight, doctors in the area do not advocate the consumption of anything boiled in human waste.

Even more amazing than the process itself, is how vendors acquire the urine for boiling. They actually place buckets at primary schools for young boys to pee into. The buckets are then collected through the day and used to make the delicacy. For the most part, the practice is accepted throughout primary schools in Dongyang. However, boys who are sick are asked to refrain from using the buckets, to keep the process of boiling eggs in urine as hygienic and healthy as possible.