Overview
The testicles of calves, lambs, roosters, turkeys, and other animals are eaten in many parts of the world, often under euphemistic culinary names. Testicles are a by-product of the castration of young animals raised for meat, so they were probably a late-spring seasonal specialty, though nowadays they are generally frozen and available year-round.
Cookery
Testicles are cooked in a variety of ways: sautéed and sauced, fricasseed, deep-fried with breading or batter, in pies, poached, roasted, and so on. Before cooking, they are generally scalded, skinned, and soaked in cold water.
Names
In English, testicles are known by a wide variety of euphemisms, including "stones", "Rocky Mountain oysters", and "prairie oysters". Lamb testicles are often called "lamb fries" or simply fries (though that may also refer to other organ meats).
Euphemisms are used in many other languages. In Arabic countries such as Lebanon, Syria and Iraq they are known as baid ghanam and in Turkey they are known as koç yumurtası which in both languages mean "sheep eggs".
From Wikipedia (CC BY-SA 4.0).