This one was sad. Reminded me of growing up poor.
And he dad was such a passive aggressive jerk. You don't shit on your little kid telling you about their day like that! Also, what's wrong with carrying cake in a container? Why does the size matter if it's a paper box???
So many emotions, so little sense.
A relatively late reply, but I wanted to say that the girl's dad might've felt upset with himself for not being able to give her what she wanted. If you had someone you loved (be it your child or lover) and they came home happily talking about someone else and what they can do/are compared to you, it kind of hurts. As a provider, he might have felt inadequate, or at least unappreciated, and while it was cruel of him in a sense he is human too.
Also, I'd imagine it's just the expectation of seeing a box that big and finding only one cake inside. But yeah, I dunno.