"Oy!" yelled the twins from the portrait hole, looking dramatically scandalized by the suggestion that Quidditch was a waste of time. Fred said, "We don't want you anyway!", and George added, "Good riddance!" with an almost stylized pompous air. It was probably a mockery of Percy himself, who apparently was the only member of his family capable of a reasonable level of responsible seriousness, but frankly Percy was completely okay with mostly-affectionate mockery if it would get him out of Quidditch. So he just nodded agreeably.