Two true anecdotes - mouse related of course.
First one is not so interesting. I used to have a trackball which on some days, would refuse to work correctly. The cursor was all over the place and moved in random directions compared to where I was scrolling the ball. Problem traced to excessive sunlight coming through the window and onto the trackball. Resolved by dismantling the thing and spraying the inside of the case with black paint from Halfords.
Second story - my own technophobe Dad went to his local library for some computer familiarisation lessons (much to my surprise). He took my step-mum along with him for support (also never used a computer in her life). Anyway, they were let loose on one of the library PCs after a basic explanation from the tutor.
My Dad relates that after a while, they had to call the tutor over, because they'd run out of desk surface with which to use the mouse. Not realising that in some situations, you might need to pick the mouse up and start moving it in the same direction (depending on various resolutions I guess), he'd got my step-mum to sit in front of the monitor and call out directions, so he could click on a particular part of the screen.
He was several feet away from the PC by now, when he ran out of desk.
Reminds me of The Golden Shot on ITV (I'm showing my age now).