Tu Quoque...I Don't Know How to Say It Either!

I was starting to become frustrated because I was almost to the bottom of the list of logical fallacies on the “Logical Fallacies and the Art of Debate” article, and I wasn’t finding anything that sounded like something I had trouble with in arguments. Then I came to the final example on the list, the Tu quoque, or the “you too” fallacy. I immediately started laughing out loud and knew I had found my weakness.
Tu quoque (I’m going to keep it in it’s Latin form because I find the language interesting, haha) is the fallacy of defending your argument by pointing out the fact that your opponent has done the same thing before. An example of this would be saying that it is ok to run a red light because you saw a police car do the same thing. I found it interesting that the article said this fallacy can actually be useful because it can determine who is doing the better job in the argument, which is something I might be able to use in my next debate!
Now I realize that the assignment was probably supposed to be geared towards argumentative essays, or actual organized debates, but I actually don’t use this form of fallacy during those kinds of arguments. I am on the other hand, guilty of this fallacy in a different kind of argument. I have often used the tu quoque tactic in many pleasant “debates” with my girlfriend, sometimes with success, but in more cases than not, with failure. I became aware of the fact that I am guilty of the “you too” tactic after my “opponent” pleasantly pointed it out to me during one of our debates. Of course, my natural response to this accusation was, “well you do it too!.”