Well it depends on the severity of the lie. I mean sometimes people just casually and absent mindly lie about stupid stuff just for the ease of explaining things. These lies are pretty harmless, and would really cause more harm to make a big deal about than to ignore. But then there are lies that are big deals like "Where have you been? " "Was hanging out at the mall." when really the person was doing something they don't want to admit to. Ultimately you are going to have to think about if bringing the lie out into the opening and discussing why the other person felt to lie will end up going well and be productive, or if it will cause more stress and annoyance than any potential fix it may make. It really depends on the situation, the other person, and how you handle it. Good luck =)