When I was a kid attending Catholic school in Rhode Island, during lunchtime in the cafeteria we were offered a choice of milk: whole milk, chocolate milk or coffee milk. If we know each other, I’ve told you this. Being from Rhode Island is the only interesting thing about me.

So I mention it all the time. That invariably leads to coffee milk, which the Rhode Island General Assembly designated as the official state drink in 1993, and is something of a regional curiosity even among the rest of close-knit New England. Chicago, I am telling you this because you’ve watched your edible quirks jump state lines and lead to misunderstandings: When tourists aren’t around, you eat way more tavern-style pizza than deep dish, and despite the plot of “The Bear,” Italian beef is a once-in-a-blue-moon indulgence for many of us and nothing like a go-to everyday lunch.

Chicago, I am telling you this because Dunkin’ just introduced coffee milk to Illinois. Actually, it offered coffee milk to the entire nation at once, courtesy of its new fall menu. Seeing it on a drive-thru screen the other day, I was startled, delighted — then uneasy.

Here was an international corporation (albeit one rooted in New England), deciding unilaterally to spread a regional secret, one that for the past century or so has been a distinctly Rhode Islanders-only treat, thank you. To get ahead of the confusion sure to result, I figured I’d explain — except Dunkin’, anticipating the nose crinkles, is a.