The small bits of excrement that stick to your arse hair. This can be reduced if not eradicated by wiping your arse properly. Restricting your intake of vindaloos and hot kebabs will reduce the likelyhood of suffering from rugnuts. As will getting a crack wax.
Also see 'Klingons'.
"Please do not be alarmed by my squirming vicar, I'm suffering from a bad case of rugnuts".
"Excuse the smell Jeremy, I have a bad batch of rugnuts".
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)