It's a quote from something; Gunn can't remember what. Not Gilbert and Sullivan.

"Yeah," he says, simply. There's a crack in there somewhere about his boyish good looks, but he doesn't want this to turn into that kind of fight. He's trying not to want this to turn into any kind of fight -- get hooked on that kind of onedownsmanship and next thing he knows, he'll be played for a sucker like Wesley was.