"Carl the Intern" is a song from the Phineas and Ferb episode "Swiss Family Phineas". The singers sing this song because Carl is being the backup for Agent P. He is riding an ice cream truck and snatches Perry after the ride. In a later episode, "Undercover Carl", another version of the song is played which include Carl alternating disguises and costumes. The song is also heard in "I Was a Middle Aged Robot" and "Tri-State Treasure: Boot of Secrets".