Rosetta stoned makes sense, becuase the Rosetta stone was used o decode or decipher the other languages. Stoned, being the drug trip. This song relates to someone coming out of a trip and trying to get all the info down before they lose it, as if they experienced something so important, that if they don't write down every nuance and go back over it, will somehow miss out on something very important, Forgot my pen=will I remember it when I return to my nondrugged state.