As a kid, someone showed me how neat it was to hold a piece of OOOO steel wool over both terminals of a D cell flashlight battery, and watch the charge turn the wool fiber golden making the connection. So hey, if it's that neat on a D cell, it must be spectacular on a car battery. Exploded the battery and blew acid on my face and in both eyes was spectacularly stupid. So yeah, I shorted out that battery. (Five steps to a big basin sink, which I backed completely down into and turned both faucets on into my face/open eyes full blast for a few minutes, and no acid burns at all.) Lucky, stupid and lucky.
I also suck at auto electric, smoke testing most everything I touch, so I don't touch it anymore. I'm pretty good with fuses, if I'm careful.