The souvenir shop is the final stop on the zoo trip. Nana usually treats them to something small, just because.
I’ve tried to sneak her out without in the past, but she enjoys doing it for them.
They appreciate it (and the gifts Nana got them, these were actually from the dino gift shop) but you can tell they were also getting tired and hungry at this point.
It’s a little harder to say no when it’s officially Superman’s birthday.