I jacked the rear right corner up to change the fuel filter. Obviously i wanted to put a stand there too in case the jack fails. Well, there aren't many good places to put it when the jack is already taking the jacking point but i found something i though was a visible part of some frame in front of the fuel tank. Don't have a picture but it was around 4cm wide longitudinal piece with 2 holes, around 12cm long. I put a stand under it and came out of the car to lower the jack to get the weight of the car on the stand.
My jack is a bit sensitive to release and it went down fast and so went the whole damn car! The "frame" was but a piece of thin steel and the stand went right through it. Luckily there was enough free space above it and the stand didn't break anything inside.
Just made me thought that my kid is a lucky guy to still have a father. What if it had gave up a bit later after i would have been under the car...
That's the reason i always use at least one stand when jacking the car and always let the full weight on the stand to see that it holds.