gaffer, gaff - meaning and definition. What is gaffer, gaff
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What (who) is gaffer, gaff - definition

SHARP-HOOKED POLE USED TO SPEAR LARGE FISH
Gaff (fishing); Gaff hook; Flying gaff; Gaffing

gaffer, gaff      
Used in place of stupid or silly.
I believe this is a very loose translation of the dictionary definitions for foolish talk, humorous old man.
Anyone a bit silly became a gaffer, and, ergo, some silly thing or act was gaff. Popped up in SE Mass around 1984.
Did you see that guy arguing for an hour over the lightsaber fights in Star Wars and how in Empire they cut through the railings, and in Jedi they didn't? What a gaffer! Have you ever see a thing called a Chick Tract? How utterly Gaff!
Gaffing         
·p.pr. & ·vb.n. of Gaff.
Gaffer (filmmaking)         
HEAD ELECTRICIAN FOR FILM AND TV CREWS
Gaffer (motion picture industry); Gaffer (filmmaking)
In film and television crews, the gaffer or chief lighting technician is the head electrician, responsible for the execution (and sometimes the design) of the lighting plan for a production. The gaffer's assistant is the best boy electric.

Wikipedia

Fishing gaff

In fishing, a gaff is a handheld pole with a sharp hook or sideway spike on the distal end, which is used to swing and stab into the body of a large fish like a pickaxe, and then pull the fish out of the water like using a pike pole. Ideally, the tip of the hook/spike is placed under the fish's backbone.

Gaffs are used when the weight of the target fish exceeds the breaking strength of the fishing line or the fishing rod and thus typical angling retrieval would be problematic. A gaff cannot be used if it is intended to release the fish unharmed after capture, unless the fish is skillfully gaffed right in the lip, jaw or lower gill using a thin hook.

A "flying gaff" is a specialized type of gaff used for securing and controlling very large fish. The hook part of the gaff (the head) detaches when sufficient force is used, somewhat like a harpoon's dart. The head is secured to the boat with a length of heavy rope or cable.