Two smoky tales
Me and my brother, we were playing some games on my 1st computer (ZX Spectrum+2!) for a couple of hours. I suddenly noticed that there was smoke coming out from the monitor's top, but it was still working. After a second or 2 looking at that, I quickly stretched out an arm to grab the power cord and pulled it out of the wall socket by the cable.
I connected everything on my 2nd new PC, powered it on and was happily (yeah, right) seeing Windows 95 booting. When it was almost done, I noticed my room getting entirely filled with smoke, the PC was shooting smoke from the back (psu fan powered) like a disco smoke machine (but darker smoke). Had to open the (room) windows before being able to go hunting for that power cord again (the PC did actually work normally after this event, but I returned it).
Funny thing these boxes today, stop working when smoking.