Shank your nan is a term roadmen use to intimidate people. Shank means stab. And your nan is commonly used among the new generation, for example “suck ur nan”.
Will-“if you tell them mun, I’m gonna shank your nan”.
James-“sorry man I won’t say a word”.
Will-“shut up or I swear blud, I’m gonna shank your nan”.”go suck ur nan”.
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)