11 hours ago, JeanneCake said:'' licking a battery? Who does that? and why?
It only worked with this type of battery as you needed to lick both terminals together.
It was done to test if the battery still had a charge or not. If it was fully charged you got an uncomfortable 9-volt shock; if dead, nothing. Your saliva completed the circuit. It wasn't that unpleasant but I sure wouldn't want to be eating 9-volt chips.