Little boxes on the hillside,
Little boxes made of ticky-tacky,
Little boxes, little boxes,
Little boxes, all the same.
There's a green one and a pink one
And a blue one and a yellow one
And they're all made out of ticky-tacky
And they all look just the same.
The song is a criticism of suburban housing developments, which the show uses to lampoon the fictional town of Agrestic.
Well, I did a little research (Wikipedia) and it turns out the song was actually written about DALY CITY!
Who knew San Francisco's closest southern neighbor would be held up as the model of suburban conformity. Clearly, critics have never hung out in downtown D.C., because it's a pretty odd place.