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.
[This comment was removed]
In some cases, and in some countries, they still do.
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.
[This comment was removed]