Jack resists the urge to chuckle as it occurs to him, despite the other's attempts to appear older how young the other man must be. No wonder he's hiding even more in his cynicism and sense of knowing. As it is, he lets a sly smile come to his bony face.

"Oh I can think of one reason that you're demonstrating quite well, why you would be asked." There is a tease in his voice, and a calculated hint of condescension designed to draw the other out further. They haven't even been properly introduced yet, but Jack figures fair is fair, given how he was addressed earlier.