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.

I was watching the ep on YouTube, and I tend to have headphones because my laptop's speakers aren't too good, so that's how I caught it. Even when YouTube compresses the heck out of the sound, you can still make out details.

The sound mix is also one of the things I love about the series. In scenes where the characters are outside and talking, the acoustics are adjusted in such a way that they actually do sound like they're outdoors (voices echoing off buildings, etc). Most other cartoons don't even bother with such details.