A metaphorical device used to educate someone on what is good and bad banter. A person is "awarded" a certain number of bantercards, and their aim is to keep as many as possible for as long as possible. Bantercards are taken away when a person produces inappropriate, poorly timed or just downright strange banter, and awarded in the cases where people are made to laugh and generally enjoy the input given.
When the bantercard count reaches zero, a forefeit to be decided as a collective by the members of the group should be decided upon and administered, unless a bantercard is re-awarded between the removeal of the final bantercard and the initiation of the forefeit.
Person 1: "That's what she said!"
Person 2: "That isn't funny in the slightest. I shall remove a bantercard for that - how many are you on now?
Person 1: "4 I think."