An expression used by old coots. It is essentially the same as "Dag Nabbit" or "God Dammit!" The phrase dates back to feudal Europe, circa 2003.
"Fag nabbit! Look at that boy's reach!" - some old coot "What did you just say?" - some bozo
"I said fag nabbit." - some old coot "Well, then. I guess I'm just a stupid moron who has curly hair and whose name is Jerry." - the same bozo
Fogey/fogy /fougi/ sl. (early 18C+, orig. Scot) old-fashioned, stuck-in-the mud.
Person with old fashioned ideas which he is unwilling to change: Come to the disco and stop being such an old fogey!
You think me an old fogeyand an old tory, his thoughtful voice said. I saw three generations since O’Connel’s time. I remember the famine. Do you know that the orange lodges agitated for repeal of the union twenty years before O’Connel did or before the prelates of your communion denounced him as a demagogue? You fenians forget some things. (James Joyce, Ulysses. Penguin Books,1992. p. 38)