227-0765. That's the phone number for Regina Pizzeria in the North End of Boston. Area code 617. I regularly forget which name belongs to each of my three kids when addressing them, and I don't always remember their cell phone numbers either. But that Regina number comes into my head without thinking. 

I imagine I learned it before I was even a teenager. My guess is that my Nana, who lived across from the Copps Hill Cemetery in the North End, told me to look it up once. Or maybe she told me to call 411 directory information back when that was a thing. Since then, it's the number I never forget.