BZZZT. Oh.
Many moons ago I worked in hardware maintenance. We had contracts for a county council (no names, no pack drill), and they had a problem with a monitor attached to an old Amstrad PC (the first ones they did). These particular PCs had the PSU for the whole thing buried in the monitor rather than a separate ones for display, CPU etc. One power cable means less mess, right?. Amstrad had obviously learned a lot from their CPC range of home computers.
I turned the monitor on, saw that nothing happened, and went for it. I did the usual of re-solder the joints on the tube neck PCB, checked for dry joints elsewhere, checked a few capacitors, and made sure that the distinctive smell of magic smoke was not present. With the case of the monitor still sat on the floor, I reached to the back of the monitor and pushed the power button.
After a fleeting, well known tingle, all the lights went out in the room I was in. And the un-occupied room next door. The wall sockets weren't working either. It turns out that the tingle was due to my little finger resting across the two solder points of the main fuse in the monitor and throwing the RCD. It turns out that little fingers are amazingly good conductors of 240v AC electricity.
I found my site contact, made my excuses, said I needed to take the monitor to the workshop for repair, and left quickly.
As a follow-up to little fingers being good conductors, I once discharged a different CRT monitor through me by having said small phalange touching the screwdriver I was using to short the tube to earth before dismantling it. That was in the workshop though so no real damage done.