"Spring is Here" is a song sung by Baby Lamb in the Season 2 episode "First Day of Spring", where he is happy about the arrival of spring. It is a parody of the song "Spring is Here", originally from Sesame Street.
Baby Lamb: Spring is where the kids in the world get a week off from school.
They get to have a break, have a little fun, and play where the air is cool.
Having lots of fun and Easter egg hunts, and lots of rain as we speak.
Until you realize another truth, we have to come back next week.
And that means spring is here.
Bunch of peeking out and the air smells sweet.
Everybody come out on the stoop.