Billy Dilley Main Title Theme

 is the opening theme to the much longer titled Billy Dilley's Super-Duper Subterranean Summer. It was produced, written and performed by Jeremy Fisher who also composed the ending theme "Catch Me if You Can".

Lyrics
Doo-doo-doo-doo doo-doo Doo-doo-doo-doo doo-doo

Billy Dilley We're subterranean

Billy Dilley You're such a brainy kid

Billy Dilley It's fascinating how

Billy Dilley It's complicated now

Billy Dilley Situation critical

Billy Dilley I hope it's fixable

Billy Dilley Oh, oh-oh-oh-oh-oh

Billy Dilley!

Trivia

 * The lyrics include the word "fascinating" which is the title character's catchphrase.