Teacher (in his thirties) said he couldn't join in the staff rota for loading the dishwasher because his wife did all that sort of thing, so he didn't know how to.
He got a very smiley - and completely non negotiable - practical instruction session in front of the entire staffroom on how to scrape off plates, remove teabags, stack the machine, where to find the tablets, how to place the tablets in the dispenser, how to close the dispenser, how to shut the door, how to programme it and how to switch it on, then wiping the surfaces with the appropriate spray and cloth.
I didn't lift a finger myself on the grounds that the desired learning outcomes indicated he would benefit from a totally enactive learning opportunity. And, as part of the What Went Well (he did it all) and Even Better If, I made a very chirpy suggestion that he did this at home, too, as it would be a very good thing for his wife to see that he's a grown up and not a barely housetrained NQT fresh out of Halls anymore.
He did start by looking across the staffroom for an ally. They all abandoned him to his suffering.
Six months later, I overheard him ticking off one of the NQTs for putting their breakfast bowl on the side with blobs of Weetabix and milk still in there with the spoon.
I'd learned that one from a) having DP needing to know how to use a dishwasher because he'd never lived anywhere that had one before (although he asked how to use it) and b) watching The Simpsons, so I knew all about strategic incompetence.