Someone who is either an
idiot, or spends too much time taking
drugs. Someone who shows signs of minimal intelligence and/or
common sense.
This phrase can be used in an offensive or a friendly context.
"Look at that
prick, he's fuckin tuned to the
moon, so he is"
"Ah've
goat my giro, ah'm gonna be well tuned tae the moon the night so ah am"