They can NOT be for real since that would be illegal in pretty much any country, but with special FX, you can always "dress" a dead animal's testicles, such as pigs, and try to pass them as really crushing a human nut.
Once you realize that people actually eatsdead pig's testicles, then I guess crushing a dead pig's testicle is just like crushing food.
Check this link for the so called food:
http://news.bbc.co.uk/2/shared/spl/h...ght/html/8.stm