A blithering idiot is someone so devoid of intelligence
that they run around
screaming their inane
little thoughts until you just can't take it anymore
and must do away with them.
These people are everywhere: they're the idiots who rule the world and the village idiot.
When saying the words "blithering idiots" you should endeavor to sound as much like John Cleese as you can and as little like Johnny Cash.
Please also see: blundering idiot, complete idiot, idiot convention, moron, simpleton, fool, ass, chowderhead, imbecile, nincompoop, sop, dullard, oaf, dunderhead, noodlehead, numbskull, halfwit.
fortuna favet fatuis!