I have a Canon printer in the room with my desktop computer. It is connected via the house wi-fi. I was sitting at the computer just now and suddenly the printer burst into life. Which was surprising as I wasn't printing anything.
I did wonder if a neighbour had somehow accidentally connected to my printer - unlikely, I know - but what came out was obviously something I'd printed.
Some months ago I came across a
website that publshes a daily killer sudoku and I print each one out because I find it easier to do on paper than online. Sometimes I remember to print it out from my laptop when I first go through my e-mail after breakfast, sometimes I forget and print it later from my desktop. The printout just now was Monday's puzzle. Now, I think I tried to print that out from my laptop on Monday morning and got the message that the printer was offline, so I printed it out again when I got to the desktop later that morning.
But quite why it has taken four days - and I have printed many other items in that time - for that printout to come through, I have no idea.