Hey, Her Bethness used "supercalifragilisticexpealidocious" in a bluegrass song ("Syllables for Sale"). Yes, it had been used before (only once, though)--but she made it rhyme with something.

I think the whole dictionary is fair game. Yes, one needs to be different--either saying something new, or something old in a new way (there is no point in plowing ground already tilled by folks more famous)--but I ain't avoiding words. If my dead animals need that "heart/apart" couplet, for instance (and considering that they're dead, they may), I'll use it, and not worry.

Joe