Margo II

If Margo liked you, trusted that you were basically a good person who was about to make a not so good decision she would say something like, "Don't be a jerk."  I liked this type of phrase because it does not accuse you of being a jerk.  It is not judgmental.  It says that you are not yet a jerk, but if you go down a certain path, that is the path of jerkiness.  You are a good person with options.  Of course, me being somewhat dull, I would have to ask her what she would recommend.  She would give a solution and then give the reasons why she would choose this particular solution.  So I would have a chance to learn something as well.  If you tell someone to their face that you think them a jerk, then they will resist any change.  They will not listen to you.  Beware of the bruised ego.  It has trouble changing course.