More on vanity key sizes
A woman with a 32-inch bust would have worn a Size 14 in Sears’s 1937 catalog. By 1967, she would have worn an 8, Ms. Zulli found.
Today, she would wear a zero.
Holy cow! I'm not sure how many bits of useless padding in a cryptographic key that would correspond to, but it's almost certainly more than just a few.