Guitar Ego (warning -- complaint ahead)

I get one student every year who has picked up a few things on the internet before coming to me and has therefore decided he is a hotshot player who does not need to learn how to read the notes on the staff, or keep time with the rest of the class when playing ensemble pieces, or basically do anything I say.
But then, to make things worse, this guy (and it is always a guy, unfortunately) finds it necessary to play all his hot licks, out of tune, while the class is trying to tune, and try to teach his neighbor to do the cool things he can do, while supplying misinformation about said cool things.
My message to this guy is simply this: you can't get humble enough to learn how to play "Twinkle Twinkle" in G from standard notation. What really important and useful information are you excluding from your life, because you are too cool?
Ok, try it again. From the top. In tempo please.