The Penance Box is a way of saying somebody has done something stupid, offensive, etc. To be in the Penance Box means you are in debt to that person and need to make it up to them promptly and appropriately.
If a friend of yours spent months moaning about someone, that person may choose to put you in his/her Penance Box for being such a moaner. A good way to repent would be to buy him/her ice cream or some other tasty treat.
by SarahBogli August 23, 2009