You nit
My physics teacher was a Grimsby town supported, his name was Mr Cheetham. He wore a tweed jacket with elbow patches and was obsessed with units. If we got the units wrong on our homework he'd write "You nit" on our work. He thought that was funny and so did we. You nit is a very polite way of saying some one is, well something not so polite.
How many times do students get an answer wrong because of the units. My students do it all the time, a right bunch of nits.
The drawing isn't of Mr Cheetham it's me. My new hobby, drawing cartoons. i'm using them to illustrate my new revision website. I hope my students will find it fun when they find themselves introducing a problem.