Well, the oldest person in recent times, Jeanne Calment, lived to be one hundred and twenty two years old, so that's probably about the limit - unless you go Biblical, when it goes up into the high nine hundreds.
I must be entering my sixth decade of ignorance about blithering. All I've ever known about blithering is that idiots do it. You blithering idiot! a teacher would say to some unfortunate forgetter of homework, or thrower of paper aeroplanes, or dropper of ink-bottles.
What meaning does blithering add to idiot?
Well, it turns out that my teachers didn't know what blithering means, either, because blithering is jabbering or talking foolishly, and the blithering idiots in their classes were seldom talking.
(Blithering can also simply mean foolish, but obviously an idiot who isn't foolish isn't an idiot.)
Do I blame my teachers for using the word wrongly? Not at all. They had a jolly difficult job, and without the opportunity to say you blithering idiot in tones of utter contempt I'm not sure they'd have had an entirely adequate reason for coming in to school.
Thing Not To Do Today: any blithering. This word is a variant of blather, which comes from the Old Norse blathr, nonsense.