A multimeter is a device used to measure resistance and voltage in an object. To do this it emits a small amount of voltage itself.
If you decide to put one cable into your blood stream on one arm, and the other cable into the other arm, it will result in your immediate death. This can be done by merely ramming the probes into veins, or pricking your thumb and tapping the blood on each arm with the probes.
The reason this works is it takes very little electricity to stop your heart, and a multimeter has more than enough. The current travel from one arm to the other via the blood stream and thus, through your heart. Badaboom, you're dead. Dead as a door nail.
How did I come across this knowledge of lethal tools of science? In my technology class at school one day, we were using multimeters to test batteries and everything.
natural.resonance and I decided to see who had the higher resistance by placing the multimeters probes on our temples (no this story does not result in the death of myself nor natural.resonance, if you're wondering)(I had the higher resistance if you're wondering that as well). Anyways, the teacher comes up and informs us not to test our blood.
Naturally, the first thing I thought of was he meant if it was like laying all over the table. I assumed it would like make it change colors or some cool effect, so was about to open a wound when he told us the real reason.
Apparently, some kid in another tech class was playing around with a multimeter before class, and decided he would test his insides. Upon testing this, he...uh...well, anyways...
So that's pretty much my story.