What I hate is my printer goes KRRR! and my paper feed light and power light alternate flashing. Which means I have to turn it off before I can proceed. The worst is when it happens in mid-page. The best time? After a print job is complete. Second best? Between pages. Third best? When it only cuts off the date at the bottom.
I could go on about when it starts taking other sheets before it’s finished with its current, or the messiness of refill kits… but I’ll stop here.