Overheard at Macey's

So I'm in the baking goods aisle at Macey's deciding which bread crumbs I want to use for the night's foray into making Milanesa, when a mom turns the corner with her 3-year-old daughter and 6-year-old son, who is trying to convince his mom of something. This is how it went:
6-y-o: But Mom, you said we could.
Mom: I most certainly did not.
6-y-o: You most certainly did.
Mom (sort of chuckling): You know I didn't.
Pause...
6-y-o: Well, then can I have a baby brother?

I nearly died trying to control my laughter. They walked away and I could hear the mom responding with laughter in her voice.