This reminds me of a joke.

A man has a constant headache. He tells the doctor about it, and it turns out that it's because his balls are pressed up against the base of his spine, giving him one hell of a headache. There is no other fix, so he gets his testicles removed. Later, the eunuch goes clothes shopping, and he meets a tailor who can guess any appropriate clothing size by looking at you. He makes several guesses, each of them correct, but then the eunuch stops him when the tailor guesses his underwear size, saying that he always wears one size smaller. The tailor says, "Not on someone with your shape. Underwear that small would press your testicles against the base of your spine, giving you a hell of a headache."