Mr. Manny is a friend of Miss Nanny's. As is customary with Miss Nanny, his head is never seen either. His catch phrase is pointing out that something "...is groovy?!," while gesturing horizontally with both of his hands, bending his knees and doing a little hip wiggle motion.
He makes his first appearance in the Muppet Babies episode, "Mister Manny," during which he temporarily replaces Miss Nanny for the day. Piggy is worried about him being different, but eventually learns that differences can be a good thing.
In "Gonzonocchio," he appears to be working at the local library.