To me the phrase has lost all meaning. I actually heard a kid say it at school a while ago and I asked him " When you say that, do you mean not pertaining to your interests?" He said yes. Looking back on it, the first time I heard it was in 3rd grade, and I'm pretty sure no one knew what it meant back then. Some kid probably heard it on T.V and thought it sounded cool so he started using it, and from then on it spread like wild fire