a knownothing is the complete and total opposite of a know-it-all. the knownothing sustains itself in social circles by pretending to know what they are talking about and backing up their arguments with nonexistent facts, in the hopes that the individual they are dialoging with are less educated than themselves.
when confronted by a know-it-all, there natural enemy, they become belligerent and any air of wise sophistication is abandoned in favor of insults and off-subject commentary.
Cliff Claven, the most popular and relevant knownothing of his time has been quoted saying things like:
When some resigns or retires from a job, they are on "eternity leave". This can also refer to someone who has passed away, especially someone who worked somewhere for a long time, retired/resigned, then passed away later.
Oh I'm sorry, you didn't know that Kelly is on eternity leave? She resigned and moved to Hawaii!
With regrets I would like to inform you that my boss is officially on eternity leave. I will never see or hear them again. Ever.