Really bad movie, I wanted to gouge my eyes in the first thirty minutes.
I love the quote in response to a drug consumption question, "No, he doesn't even drink caffinee because he doesn't want to damage the instrument . . . " (Not the exact quote, I'm paraphrasing, but you get the jist !^_^!).
Now, let us analyze this. Instrument could refer to his genitals, but good ol' Katie was talking to his parents about him missing in action. So probably not.
How bout the voice maybe he's a singer. Caffinee does nothing to the vocal chords nor was the man an actual singer, he was more of a tree hugging Earth liberator.
So, that phrase to me is an absolute mystery, if you can decypher it, please feel free. And if you want a bigger task, try figuring out what creepy library girl is telling the cop when he interigates her. Good luck with that one.