I don't pretend to know anything I don't know and I was upfront with him that I hadn't ever taught and learned the ghetto way and he still wanted to learn from me. So I told him I'd teach him what I could to get him started and if he finds himself really loving the guitar and wanting to go head on into it that he should find a more formal teacher in the future. Granted he hasn't had any questions I don't know the answers to at the moment.
For instance I don't know all of my basic chords (at least not by name, but I seem to know most of the shapes looking back at it) as I only learned a few in passing so I'm going back and learning all of them to teach him and I told him that. Told him the story of my embarrassment when I went to jam with my uncle and a few guys he knows from church and they all play basically just the basic chords and have never branched out from there so when they went to show me the chords to the songs I was fumbling around doing awful at it and instead just started improving a melody ontop of the song.
So far I just covered how to hold a pick, how to fret, told him what all the major parts are on the guitar, showed him how to tune it with a tuner and let him tune it up, showed him C and A major chords / powerchord, and quickly skimmed how to read tabs. Then we started working on 'the pretender' by the foo fighters which happens to be one of his favorite songs.
Its really exhilarating to see someone go from not even understanding how one plays the instrument to getting ridiculously happy that he was able to just grab a C major chord and have his hand fall into position or start learning a song he knows. Good soup