A non-threatening threat. Basically, it's how one will show their anger to another, quickly look around for a sharp object, fail in finding one, and say the threat anyways, not being able to back it up. Usually used in a friendly manner, where the speaker (probably) won't stab the other guy, anyway.
Jack: Hey man, you know what a pelican looks like!?
John: Well, you've got the saggy chins, the beady eyes, and you are annoying as Hell, so... I'm gonna have to say, like you.
Jack: I will stab you...
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)