Sociologist Barrie Thorne has spent the last 20 years studying "cootie games," and in her book, Gender Play, revealed the dark side of this children's pastime. "Girls give cooties to boys more often than vice versa," she writes. She calls cootie games "pollution rituals," and concludes that "in contemporary U.S. culture, even young girls are treated as symbolically contaminating in a way that boys, as a group, are not."

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