This is a song sung by Peg and lip-synched by Cat in order to impress Roxanne while they were on a walk with her in The Roxanne Problem. He was lip-synching because he didn't know the words and, due to a misunderstanding, Roxanne thought Peg's voice was his voice.
Peg: Solid shapes... are the shapes for me.
Length, width and height... they've got all three.
Cylinders,... a box or ball.
Solid shapes... they've got it all.
Roxanne: Ooh, that is my very favorite song.
Peg: Then you should really sing along. Solid shapes.
Roxanne: You know I love my solid shapes.
Peg: Are the shapes for me.
Roxanne: The shapes I really long to see.
Peg: Length, width and height.
Roxanne: They're long and wide and also high.
Peg: They've got all three.
Roxanne: I sing their praises to the sky!
Roxanne: They've got circles on the ends.
Peg: A box or ball.
Roxanne: Cube and sphere are my best friends.
Peg: Solid shapes.
Roxanne: I stack on top and they won't fall.
Peg: They've got it all!
Roxanne: They're large or small, they've got it all!