The oldest trick in the book

Suppose there is a piece of information that you don't want to share with someone. Let's call it P. Suppose also that P is such that, although you would prefer not to assert P, if ~P were true you wouldn't mind sharing that information with people. You should be on the lookout for the following ploy.

Your friend (or other conversational participant) starts asking some innocent-seeming questions of the same general kind as the question: "P? Yes or no." Since you don't care about telling her the answers to these other questions, you answer them truthfully. Then suddenly you are hit with the question whether P. What do you do? If you deny P, you will be lying. If you refuse to assent to P without denying it, it will be obvious that you believe P, since if you didn't you would have no reason to refuse to deny it. The problem is that, in the context created by the innocent-seeming questions previously asked, refusal to assent ends up indicating assent, so that it is not possible to avoid providing the information you hoped to withhold short of lying.

The way to avoid this is to be aware of the danger and to refuse to offer assent or dissent to propositions of the same general kind as those that you want to keep to yourself, even when you don't have an interest in keeping them secret. For example, it might be a wise policy, when you don't want to tell the friend of someone you have a crush on that you do, to refuse to comment generally on any other crushes you might or might not have. Then a refusal to assent when asked cannot be interpreted as anything more than an instance of this general policy.

However, this strategy requires foresight and an ability to tell when a conversation is veering into dangerous territory. This is much harder when you are drunk.