By "Kill George" do you mean once or permanately? Because it's not that difficult to kill him it's just that he respawns after a round but if you mean permanantly I have no idea. I did see a youtube video once where someone permanantly killed him but I have no idea how (I'm pretty sure it was a glitch). Anyways though, my highest legit was 26 (haven't actually even gone for a super high level just doing the easter egg and then messing around). I've also gotten to 36 with a friend doing the barrier glitch at the foot of the lighthouse, just for the lulz.