Apple-Tight for Destruction

Tonight at dinner, Isaac and Brenda worked out a deal that enabled Isaac to either have part of a doughnut or a handful of goldfish if he finished his dinner. Isaac asked me which one I wanted and I told him that I didn't really want either. This is what followed:

Isaac: Well, dad, I guess you won't have that or that (pointing to the doughnuts and the goldfish that Rosalie was enjoying).
Me: Nope.
Isaac: You must not have an apple-tight.
Me: A what?
Isaac: An apple-tight.
Brenda: You mean an appetite?
Me: Yeah. Appetite.
Isaac: No. An apple-tight. It's what grown-ups get when they're hungry.
Brenda: Yeah, it's called an appetite.
Isaac: Yeah. That's it.

Meanwhile, Rosalie managed to break into the top of the fishtank. I think it may have been a set-up.