I was watching "Muffy Gets Mature" a while ago. During the teenager party, a song comes on and Muffy starts dancing to it. The lyrics are from a part of Lewis Carroll's poem "A Boat Beneath a Sunny Sky", specifically this part:
Still she haunts me phantomwise
Alice moving under skies (Muffy starts dancing when this lyric is heard, possible reference to her middle name?)
Never seen by waking eyes
Children yet the tale to hear
Eager eye and willing ear
Lovingly shall nestle near
Interestingly, the female singing the song sounds a bit like Holly Gauthier Frankel, aka Fern.
It makes me wonder if any other episodes have one-off songs. I thought it was cool that they did this rather than use some generic melody like they usually do, like that Motörhead-sounding song that's always used during action sequences, or is listened to by Molly or the other Tough Customers.