Funny conversation!

To fully understand the hilarity of the following conversation I must take you back 30some years, to a time even before I can remember (if I was even around.)
When my sister was a toddler she was not so fond of bath time. Being that most Citrenbaum's are far from water-babies this is not such a surprise. Any time it was bath night, Amy would demand in her mighty toddler voice "But I cookin' a baf yesterday!". My dad has repeated this line so many times in my life time that I am not sure if I am part of this memory or simply a recipient of the story.
Last Sunday night my parents were over for dinner. We were getting ready for bath time and my dad was sitting on the steps playing with Ryder. Chase was excited to take a bath, and approached the steps to see the Pop-Pop/Ryder blockade. He said "'scuse me Pop-Pop" as he made his way past. (Kudos to the manners.). My dad said "Where you going Chase" and he responded "I am going to take a bath.". My dad responded, as expected, with a "but I cookin' a bath yesterday.". His reaction was a reflex, a habit of years of practice. It was rhetorical, of course, something my mom and I would have barely heard if it was not for Chase's questioning response. His voice rose just slightly at the end intonating his question, as he looked at my dad and said, "You Did?". We all laughed, which Chase loves, so he laughed too, not knowing what was so funny.