A misunderstanding of the old scientist/techie joke that a millihelen is the amount of beauty needed to launch one
ship. Milli- is the international scientific prefix for 1/1000. Most international units are named after someone -- watt for power, newton for force, ampere for current, and so on. Scientists, techs, and gears who
work with those prefixes all the time often attach them to all sorts of made-up units. So a megahelen would be the beauty of a face that launched a billion ships (one million times one thousand) and a nanohelen would be the face that launched one millionth of a
ship (one billionth times one thousand). Millihelen worked better a few decades ago when newspapers and
TV news often carried stories about ship launchings, because usually the woman christening the ship launch was a First Lady, the Queen, or some senator or lord's
wife (what nowadays we call a first
wife, the one before the trophy
wife), and thus a lizardy old bag that was only sort of recognizably
female.
"That one's a mini-
Helen."
"Unless she's a real cute
midget, you mean she's got about a millihelen. Go back to chemistry class and
stop getting your science from Star Trek reruns!"