Christmas Amnesty. You can fall out of contact with a friend, fail to return calls, ignore e-mails, avoid eye contact at the Thrifty-Mart, forget birthdays, anniversaries, and reunions, and if you show up at their house during the holidays (with a gift) they are socially bound to forgive you-act like nothing happened. Decorum dictates that the friendship move forward from that point, without guilt or recrimination.