Severus was actually a bit relieved that the boy unwrapped the chocolate bar for him. He normally just ... tore into them, but if the wrapper was speaking, the idea was more than a little unnerving, all of a sudden. And as he picked up the chocolate bar, he eyed it warily, sincerely hoping that it didn't suddenly start talking, as well.
He started to take a bite, but then paused. Then he started to shake his head at the boy's question, a 'no' already forming on his lips. But he paused again, with a, "Yes -- you can tell me how you're making these things ... talk." And he shot another glance at the chocolate bar, still hesitant to bite into the thing.