As a kid growing up in the Northeast, I had no idea what grits were. I thought "Kiss my grits" was something vaguely naughty, like "Kiss my butt".
I can see the implication as drawn from a kid's view without knowing what grits were.
Imagine my disappointment to find out it's just breakfast mush.
I'm a born and bred South Georgian, so I'm very familiar with grits. It was one of my favorite breakfast dishes, served with butter, salt, pepper, and a good portion of cheese for good measure. My mother-in-law even sometimes makes them with cream cheese in them, and they're delicious, I assure you.
Imagine my horror, however, when my mother took my to her new in-laws' house several years ago. They had grits, but no salt, no pepper, no butter, no cheese. They had sugar in them. Sugar! And it was gross.
They aren't married anymore, though.