You'll get a kick out of this story.
So about 10 years ago my wife and I moved into a pretty rough rental. It was one of the only houses we could afford to rent at the time and we wanted to get out of an apartment. At the time I had a PC with a cable-card in it and used it as our main TV receiver.
So we move in, I get the TV and PC setup. Last thing to do is connect the TV cable. I have the cable in my right hand, and I'm using my left hand to touch the computer - ZAP! Shook it off, tried again - ZAP!
I spent some time thinking and decided to grab the multimeter. The outlets were dishing out the 120, but the ground wasn't pulling it. I searched forever and found the ground wire completely unsecured in the basement; just touching a water pipe but not clamped. "Fuck!" I thought. So I turned off the power to the house (I think? Shit maybe not) and then secured the ground to the pipe so I didn't kill myself in the meantime and called my landlord to get an EE out quick.
Holy fuck, man. Not only was it not secured to the water pipe, BUT IT WASNT EVEN THE WATER PIPE! It was the god damn gas line. I still get the glad-im-not-deads to this day.