That unnerving feeling when something has gone horribly wrong while doing work and your anus tightens up in a flinching and constipated way. It's a form of panic attack when you realise your life / career just ended and you go into a wild panic to try rectify the situation before you get found out.
Boss: While you're updating all the systems, if it goes pear shaped, don't have a nipsy twitch, just get it fixed!
or
Worker: I hit the red button instead of the green one and suddenly felt my nipsy twitch.
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)