Carol decided to limit the number of playdates between her 3-year-old son, Chris, and his friend Paul. The boys had been fighting a lot recently, and Carol thought they should spend some time apart. So when Paul's mother called one afternoon to arrange a get-together, Carol told her that Chris was sick.

Overhearing this, her son asked, "Am I sick, Mommy? What's wrong with me?" Carol, taken aback by her son's frightened look, told him she had only said he was sick, because she didn't want to hurt Paul's mother's feelings. Carol then launched into a complicated explanation of the distinctions between the various types of lies, and Chris was confused. All he understood was that fibbing is sometimes okay-and that, in fact, it's what people do.