China is a place with many unusual annual traditions, including a mud-flinging festival in the country’s tropical southwest and a June celebration of eating worms. But one of the most exotic rituals comes in spring, when residents of Dongyang, in coastal Zhejiang Province, chow down on eggs simmered in steaming pots of — wait for it — boys’ urine.

Sold since ancient times as “virgin boy eggs,” the local delicacy was officially listed as “intangible cultural heritage” in Dongyang in 2008. Many residents believe they energize the body, improve blood circulation and prevent heat stroke. They are also a bargain at around 25 cents an egg, urine included.

Across Dongyang, a bustling city of nearly one million people, fresh urine is collected every day from buckets placed in elementary school hallways, where boys under the age of 10 are instructed to answer nature’s call — as long as they are not sick, out of concern for, um, food safety. Some vendors even carry around empty bottles and wait in parks or public bathrooms until they find a parent willing to let a prepubescent son participate in the custom.

Chinese medicine practitioners are divided on the supposed benefits of ingesting urine, which modern science has shown to have no nutritional value. But the locals in Dongyang are happy to shower praise on the eggs they call “the taste of spring.”