I knew, just like everyone knows, that if you let the gas run in the oven for a short while before lighting it, it will go boom. When the match went out, and the box of matches was very close, and I'd only need to stand up for a second to get another one, I lit the new one and it went boom. I would have been knocked several feet back, but for the very narrow galley kitchen which left only about two fee before I was slammed into the refrigerator. As others here, there was nothing worse than facial hair loss and a short-lived back ache.
Lesson learned: "really quick" is not quick enough.
But the REALLY bad one is this. I drove two or three hours after work up to a friend's house for a weekend visit. I arrived with some twinges and spasms in my upper back, shoulders, and neck, for which I'd used a certain muscle relaxant, methocarbamol, every now and then for a log time. Methocarbamol has little or no sedative effect and was prescribed for me by doctors who knew my history and other meds*.
I didn't have any with me, but my friend has some cyclobenzaprine that she uses for much the same situations. So, I took someone else's prescription muscle relaxant. But that wasn't stupid enough.
I also arrived in the mood for a drink or two. So we had a few, and a very nice time. I ended up taking five drinks along with someone else's prescription muscle relaxant; cyclobenzaprine has a strong sedative effect. When I went up to the attic guest room, I tripped on the edge of the futon, found a pillow and a blanket within reach, and closed my eyes.
Results: the best night's sleep I've had in ten or fifteen years before or since, AND a feeling of profound shock at how bloody damned stupid I'd been. Lesson learned: I'm a stupendous idiot and lucky to be alive.
(I've had cyclobenzaprine prescribed properly since then. It works very well but knocks me out so I can barely function. I like to have some of that on hand for when the spasms start and I can afford to be knocked out, and also some methocarbamol for when I can't. The latter is available over the counter in Canada, but not here in The States. I only need either one about three or four times a year.)
* The first time methocarbamol was prescribed it was not by a doctor who knew my history, but by the on campus doctor during my sophomore year in college. This guy handed out antibiotics from two gallon bottles on his desk like candy, and prescriptions for codeine for a slight cold. I woke up one morning hardly able to stand (the spasms were in my lower back that time, even though it's the upper back that bothers me much more often) and hobbled my way into a hot shower, which didn't help, then to his office since he was the only game in town. He gave me a little envelope with twenty or so pills, and instructions to take one every four hours until I was better.
Result: I only needed one, the spasms went away like magic and I felt fine. Lesson learned: sometimes even a pill pushing quack can push the right pill.