I was doing some work on the plumbing - I'm switching the entire house from copper to PEX.

At about the mid-point, when I had most of the pipes cut, I had to de-sweat a pipe. The water in the house was off, but I'd pulled out a 7 gallon water jug that we keep full all the time.

My son, not knowing I was in the basement torching a pipe, grabbed the same pipe whilst upstairs. He howled in pain, and we used our emergency water supply to cool the burn. He was not seriously hurt, but I was glad to have the water on hand.