very simply Cobs = Cobblers = Testicles = Bollocks = Nuts

All these can be used in slang in two ways and I dont really think there is any difference between english and american usage.

eg "Done my Cobs" or "Done my Bollocks" or "Done my Nuts" means Spent or Lost all my money.

whereas "The Cobs" or "The (dogs) Bollocks" or "The Nuts" means The Best (as in the Nut hand)

Going back to your past ailment. I heard that if they were itchy, that was good luck