And if a boy had a girl for a sweetheart and told lies about it then he would give him such a whipping as no boy ever got in this world. He said that there was nothing in this world he would like so well as that.
Though the old man has been creepy for the entire conversation, it is this sentence that confirms him as a perverted sadist. His earlier fixation on young women, put into context with his fascination with whipping children. sculpts the old man into a truly vile character. He doesn't just think that children need strong discipline, he thinks they need the harshest discipline possible (whipping vs slapping etc.) and takes personal pleasure in dispensing such discipline.