I'm So Happy is a song sung by The Chameleon and Verminious Snaptrap in Mission: Really Big Mission.
The Chameleon: "I'm so happy, happy, snappy, trappy—"
Snaptrap: "Uh, Yeah. We have a strict no singing policy at D.O.O.M."
Snaptrap: (Speaking) Ooooh, Now I feel like singing a song. (Singing) I'm so happy, happy—
The Chameleon: Ahem. Policy.
Snaptrap: Darn It!