Rule Number 4 - Never Say Yes To A Question

Never say Yes to a question in the first instance (especially if someone is asking you to do them a favour).  Always respond with more questions until you can fully ascertain if they are trying to land you in it or not.

If you feel yourself going to say yes, continue asking questions until the answer becomes no.  Only when there are no more questions and the user is still bugging you should you say yes to get rid of them.