haha! nice one I had a similar event when I went to turn off the water under my grandpa's kitchen sink. soon as I touched the valve it popped right off in my hand and shot 50psi in my face. so I plugged it with my thumb and tried my darnedest to, uh, "calmly" explain to my grandpa where the master shutoff was in the basement and then waited while he shuffled off. man my thumb was hurtin' by the time the pressure stopped. all the while my grandma was freaking out over the water in her cupboards. she always was one to recognize the important things in life.
or the time I was fixing a leak at my cousin's house and noticed that the in and out for the hot water tank were switched. as in, were always that way since the house was built. oops! thank god for flexy lines.
I hate plumbing I'm not even a plumber and there's no end to the stories of fixing other peoples' mistakes...