Casual sex takes many forms. You know the obvious ones: the one-night stand, the booty call, sex by appointment. More recent variations include "rec" (recreational) sex, which exists because, as one friend told me, "every great athlete needs practice." And then there's "cereal" sex, which is a one-night stand amid a dry spell that, like cereal, is satisfying in the moment but leaves you needing further sustenance shortly thereafter. Yet, every flavor of casual sex—uncommitted, unemotional, purely carnal—is governed by the same rules. We list them below to help you fornicate better.