From wiktionary:
regular coffee (countable and uncountable, plural regular coffees)
1. (dialectal, US, New England) Coffee with cream and sugar (in contrast to the expected meaning of "black coffee" in other regions of the USA).
Gimme three regular coffees and three blacks.
2. (dialectal) Black coffee
3. Coffee with caffeine (as opposed to decaffeinated).
4.(dialectal, US) American coffee, as opposed to espresso, or a derived coffee drink (cappuccino, latte, iced coffee, etc.)
Usage notes
The definition of "regular" varies distinctly with region in the United States; some regions having firm definitions and others no specific meaning. In eastern Massachusetts (as noted), and New York, it is cream and sugar, in some areas of the Midwest, it means black (neither). The usage is in diners and coffee shops; in upscale restaurants and bars it is not heard. In Canada it is commonly used in the ubiquitous Tim Horton's chain, where it refers to coffee with "one milk" and "one sugar."