Aluminum foil.
Bonus points if you have those old school metal fillings in your teeth.
I read this and instantly felt a jolt. Wow.
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It is basically mild electrocution of your teeth and more importantly tooth nerves.
http://science.howstuffworks.com/question564.htm
To get a similar feeling put a 9V battery on your tongue.
In some cases, and in some countries, they still do.
Aluminum foil.
Bonus points if you have those old school metal fillings in your teeth.
I read this and instantly felt a jolt. Wow.
[This comment was removed]