The song they sang?

After Julian comes home from the hospital, Becki and Keith start singing:
"Hail, hail, the gang's all here.
Aren't we glad we're all here,
Aren't we glad we're all here"

I thought that the song was from "The Pirates of Penzance" because my university just put that play on for Homecoming and I heard that melody when my brother played the score. BUT when I saw the play, I never heard those lyrics.

So, what song was it?

"I reccomend the creme brulee! I reccomend you go away!"