Boy’s-Urine-Soaked Eggs are Local Specialty in China (4 pics)
Every early spring, a foul odor fills the air of Dongyang, Zhejiang Province. Dongyang people call it “the smell of spring.” But actually this is the smell of urine. Boy egg vendors go to local elementary schools to collect urine from boys, preferably under the age of 10, with buckets. The process of boiling eggs in boys’ urine: first, soak eggs in urine and heat them over the stove. After it boils, get all eggs out and crack their shells before putting them back. After a while, pour in new urine. Repeat it and simmer eggs for an entire day. Such eggs are called "tong zi dan" and cost 1.50 yuan (23 cents) apiece. Local people love the taste of thee eggs and eat up to ten of them each day.
Here is a small article in Chinese Wikipedia