What clued me in was my dad, whose favorite meal was a tuna sandwich and a diet coke, insisting that Santa didn’t want milk & cookies, Santa wanted a tuna sandwich and diet coke.
When I was very little, and we put cookies out for Santa, my mom would always let me eat one because she “didn’t want Santa getting fat“.
My father happened to be on a diet at the same time. I figured it out when I was six.
From that point on, my “punishment” was to be the chief gift wrapper. I suppose the one good thing that came from that is, after many years of wrapping gifts for my whole family, I am now an expert at wrapping gifts.