I believe skippers refer to this as a "Gerk" (or "Gurk") designed to remind the crew to pay attention to the sails?
It is, indeed, known as a Gurk. That is the sound the crew often makes when this "method" is employed. Crews do not appreciate getting gurked, and some skippers are forced to move to single-hand fleets once they are labeled by the Union as a gurker. Although I once knew an F17 driver who gurked himself.
