It's not related to the Mercedes but my most famous "it seemed like a good idea at the time" moment was a few (ok, more like eight or ten) years ago when they gave me my first multimeter for Christmas, it was a pretty nice Extech 460 or 463 or something like that, it's not with me at the moment... anyway, I was just playing with it, I knew how to set it to ohms and test my tongue to see if it still had low resistance the way it did five seconds ago, that kind of thing... and I knew that I could check the voltage of a wall outlet by setting it to ac volts.
But... I asked myself.... how many AMPS does that outlet have? :-D
I didn't realize that the time that amperage was a current drain measurement and not just a static "at rest" measurement - so I dutifully plugged in a power strip (so I could reach it easier or something) and set the meter to amps, plugged the positive lead into the amp socket, and stuck it in.
Pffffffttt.... needless to say, it shorted out the power strip... the circuit breaker on the strip saved the rest of that outlet and so forth I guess... but it melted the tip of the + lead on my tester, and fried the power strip... yeah, explaining THAT one to my dad was a lot of fun
