Ah, very good point from ThunderN and it-ogo -- although муде (pl. муди) is a rude word for the testicles and can be translated "balls; nuts", it's not a commonly used word in Russian.

So if you want to translate from English "Darling, do you think it would look sexier if I shaved my balls" or "The football player was scratching his nuts when he thought the camera wasn't on him" (for example) it's much better to use яйца, which literally means "eggs" but in slang refers to the testicles.