People who are told that they must conform to moral standards which very few actually can meet are likely to conclude that morality is a set of hypocritical platitudes that only a fool would take seriously. (Think, for instance, of the reaction of most young people everywhere to the demand for lifelong celibacy, except within heterosexual marriage.)
[Mary Anne Warren, Moral Status, Clarendon (Oxford: 1997) p. 14.]
I'm thinking of it, but the example doesn't seem quite so firm as Warren seems to think. Since the demand doesn't die out, this means either that most of those young people "conclude that morality is a set of hypocritical platitudes that only a fool would take seriously" but then later change their minds; or that they don't, in fact, "conclude that morality is a set of hypocritical platitudes that only a fool would take seriously". Nor is it really quite clear that "most young people everywhere" think that the demand is a moral standard "which very few actually can meet"; I would imagine there is a lot of diversity among that very heterogeneous group, "most young people everywhere."
I'm unclear, actually, whether this was intended as a joke or as a serious example; nothing in the context marks it as a joke, and, to be frank, Warren often affirms uncritically arguments that happen to yield conclusions she agrees with, some of which are more of a stretch than this one would be if affirmed seriously. But perhaps it was a joke, or a half-joke; I can hardly imagine someone actually saying this without saying it half-jokingly. That's a problem with arguments in writing, I suppose; in reading them we operate under only partial information.