[Usenet: portmanteau, clue + two-by-four] The notional stick with
which one whacks an aggressively clueless person. This term derives from a
western American folk saying about training a mule First, you got to
hit him with a two-by-four. That's to get his attention.
The
clue-by-four is a close relative of the LART.
Syn. clue stick. This metaphor is
commonly elaborated; your editor once heard a hacker say I smite you
with the great sword Cluebringer!