Although the practice of eating bull testicles is not very common in the United States anymore, it was once fairly widespread in the West You can still find the dish in the Midwest in cattle states like Texas and Oklahoma. Internationally, Spain champions them, as do Argentina and certain places in Mexico. In Canada, they are called prairie oysters. Consuming bull testicles makes a lot of sense in areas where cattle ranching is a big industry. Bulls have to be castrated in order to control breeding or discourage aggression. And if you're already taking their balls off, why be wasteful...