Call of Ktulu

Meaning

An instrumental song.
Knuckles:  "The instrumentals idea was basically just a chance for Sonic and Tails to flex their musician's muscles.  Julie-Su actually wrote a lot of the melodies and they were very good.  It's a popular song."
Julie-Su:  "And I hate him for it"
Knuckles:  "*laughs* Yeah."

Live

A fixed part of the live performance.
Kevin:  "We used to put it at the end and I got to take off early, so to speak.  Sometimes we had the outro before the song started so I didn't have to come back, but after a while I started to feel like I was being an asshole to the audience.  Oh, well, hindsight's always 20/20 isn't it?  After we moved it, I still took off once, got a drink, and died during the next song.  Literally."

Fatnerd