False. In order to prevent the person from biting their tongue, place something in the mouth might not help the person as it may still get a bite accidentally.
We can just try to be careful and not to get a bite on the tongue accidentally or we might have to do proper remedies in order to get the swelling away.
It is a well known fact that ' tongues' and the ' insides of cheeks ' have sado-masochistic tendencies. They will purposely jump between your teeth to receive painful bit of joy.
