They’re an essential part of the human anatomy for about half the world’s population. Testicles. In most languages, the slang terms for them comes from certain obvious sources: balls, nuts, stones, eggs, etc. “Testicles” has more of an unusual history, thought.
“Testicle” is the diminutive (i.e. small/cute) form of the Latin word “testis”, which means “witness”. So the testicles are “small witnesses”. But witnesses of what exactly? Well, some scholars believe that testicles were “witnesses” of a man’s masculinity or virility. The testicles proved the manhood.
There is a more interesting theory, though. Some people argue that “testicles” are named as such because it was traditional practice for men to touch one’s testicles whenever they swore an oath. According to this interpretation, the “witness” would be forced to swear upon their manhood before their testimony would be accepted (to use a contemporary example, this would be like saying “I swear on my mother’s life”). In that sense, “testicles” were named for their important function in legal proceedings.
– A few thoughts from your friend Saxo