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In US baseball slang, a coach or player who berates or derides the umpire or opposing players from his team's dugout bench. In this usage, "jockey," the rider of a race horse, refers to "riding someone," which commonly means to harass or ridicule a person. Primarily heard in US, South Africa. I wish you wouldn't be such a bench jockey at our games!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
n. a player who sits on the bench and calls out advice. The coach told all the bench jockeys to shut up.
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.