Yes, it's 'C', and it could've been a lot of things Zappa-ish, but it has to be "Cosmic Debris". Whenever my mind wanders, "Cosmic Debris" starts up, invades my brain with that little catchy riff and then I remember those guys who I used to know, toking up in a nowhere music band environment, getting a kick out of playing the 'rock star' and doing nothing about it. I think they're still out there, somewhere...
I tried to play this once and found it quite difficult, but that didn't put me off trying :-)
You've gotta love the imagery within Zappa's songs, they're spot on!
See it here...https://www.youtube.com/watch?v=Dp6LT2MdaPI