I just heard today that "rule of thumb" does NOT mean what I thought it meant. I'd assumed (thereby making an "ass" of "u" and "me," heh heh heh) that it stemmed from the time of the Roman Emperors - who would extend their thumb upwards if a gladiator was to live, and downwards if he was to die, after his performance.
Now I've learned that actually, the rule of thumb was that a man (in what era, I'm afraid I don't know) was allowed to beat his wife and children, but not with a stick larger than the size of his thumb.
Nice, eh?
"Will you marry me?"
"Uh....let's see your thumb, first."
