Charles Grodin and Joe Bologna
Buddy is Teddy's best friend in this movie. I know from Gene Wilder's autobiography that Charles Grodin was one of his best friends from about the sixties and still is today so that was how I figured Grodin wound up playing Buddy - He was one of his closest friends in real life so he played his best friend in the movie. But does anyone know for sure if Gene also knew Joe Bologna? I think he did because he said in his book that he did work with Renee Taylor, who wound up in the Producers because Bologna recommended her to Mel Brooks, so I would guess he did.
And I'd just like it to be recorded that this movie is hilarious and highly underrated.