A clue-by-four is a term used when someone is irritatingly clueless in a detrimental way and not only needs to be corrected, but needs to be chastised at the same time.

A device that is commonly used to give someone a clue. Named as such for its appearance, which is oddly similar to a two-by-four.

(Slang)An uncommon American noun used usually (but not exclusively) by right-wing weblog addicts.

An imaginary ideological (or actual) 'stick' with which we beat someone with whom we disagree.