Let's look at the following sentence. "You know, they say you shouldn't eat too much sugar." Should there be a semi-colon after "know"? I'm almost positive that "You know" and "they say" are both independent clauses, but I've never seen sentences like that written with a semi-colon. I always see "You know, they say [insert saying]." Or, would "they say" be the direct object, and there shouldn't be either punctuation mark?