Humans are all capable of being brainless idiots at times, so what's the silliest way you have hurt yourself?
As for me, curious about if a telephone line carried an electric current I simply put the phone line in my mouth. As it turns out, they do indeed carry electricity- rather well, actually.
I also plunged my hand into a lobster tank at an aquarium in Alaska- bloody strong critters. The bruises and crush marks lasted weeks