Jowls

From Muppet Wiki

Jowls is the wrinkly-faced member of the zydeco house band on Muppets Tonight. He can be seen whistling part of the theme song at the start of every episode. He also spoke in episode 108, when Clifford asked him about a gig coming up on the weekend and Jowls replied, "Yaow,yaow...Ooo...you cool?" and then Clifford replies, "I don't understand what he says either."