In American superstitions, the number three is very important. Often, Americans will say, "All things come in threes." Three is lucky because it represents the traditional family: mother, father, and child. Therefore, gifts, letters, and guests will often arrive at your home in groups of three. However, it is also possible for bad events, like accidents and funerals, to come in threes as well.

在美国迷信中，数字“三”很重要。美国人常会说“无三不成礼”。三是个幸运数字，因为它代表了一个传统的家庭︰母亲，父亲和孩子。因此，礼物、信件和客人常常会成三出现在你的家。不过，事故和葬礼等不幸的事件也有可能会成三的出现。