From Zappa Wiki Jawaka
Marty Perellis, originally from Maryland, was FZ's road manager for a number of tours during the 70's. His antics, and sexual experiences, provided Frank with many of his most famous "bits". Marty provided vocal for You Can't Do That On Stage Anymore Vol. 3, and cannot be seen (because he's in a gorilla suit) in the Zappa movie Dub Room Special.