Which old comedian is Bobby Hill imitating what he pulls up his pants and says "what are you talking about?"?

On a few episodes of King of the Hill, starting in episode 8 season 1, Bobby Hill will pull up his pants really high like an old man and walk around saying "What are you talking about? What are you talking about?" With an accent that I think is Jewish, maybe German. He says it like "Vat are you talkin' about?" I tried Googling this to find the reference but had no luck finding it. I'm guessing it's just some old TV star or stand up comedian, but I'm curious as to who exactly it is. Thanks in advance!