Hack Of The Night : How to test a battery without putting it on your tongue

You've probably heard before that you can test if a battery still has some juice in it by touching it to your tongue.  If you get a bit of a shock, then the battery is still good.  Personally, I don't really wanna do that because it seems gross.  Not that my tongue hasn't been in dirtier places, but that's a story for another time.  Plus, what happens if you do that and your head gets electrocuted and explodes?  How am I supposed to wear my headphones if my head just exploded.  Answer me THAT Dr. Dre...  Turns out that you can test a battery, and you don't even need to put it on your tongue.  Do this instead..