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A member of a construction crew who stands in the middle of a two lane road with a sign that says "STOP" on one side and "SLOW" on the other. In concert with his counterpart on the other side of the project, he alternately stops traffic and then lets it pass. Not generally regarded as a very rewarding career path.
Better stay in school, son, or you could end up like this guy: a human stop sign!
by PBSPinchback June 19, 2011