Jack was relieved, on a couple of levels. One of them was that he didn't now, after the impulsive dare, want to have to find a way out of even a joking offer to feed Klaus. The other was that he in no way liked teenagers enough to want to hang out with them: he consistently made them cry.

Jack was just not a kid friendly person.

"I'm sure, like wine, they'll all be better with at least a decade to mature. Unless they turn into vinegar. Art Fair, then? Or would you rather me keep tossing out suggestions until I hit on something that really appeals to you?"