Net judge

A tennis official who hasn't much to do. His job is to sit on a chair between the umpire's stand and the net post, keeping a finger or two on the top of the net cord on all serves, so as to judge officially whether a let ball should be called as the result of a service having nicked the cord, in which case he will feel the tremor on his finger. Since, when this happens, almost without exception everybody in the place realizes it happened, either because it's obvious visually, or the tick is heard, or both, the net judge is by-and-large an unnecessary official, and is more to be pitied than censured.