Byob is an acronym that has several possible sources, and even several possible alternative symbolized words. But all have the same ultimate meaning: You are invited to an event, but if you want anything to drink you’ll have to bring your own (BYO).

Bring Your Own Bottle, Bring Your Own Booze, Bring Your Own Beverage, Bring Your Own Beer … the detail is irrelevant. The initials mean the same thing on party invitations and in unlicensed restaurants across the English-speaking world.

The term can be traced back to the 1950s, though it is uncertain on which side of the Atlantic it was first coined. The fact that it has so many different variations strongly suggests that it emerged spontaneously in different locations.

“BYOB” became popular in England in the 1970s, in the aftermath of the rise of supermarkets that sold drinks more cheaply than pubs, prompting a long-term shift to home-based drinking away from the traditional pub. At the same time Britons also began to eat out in restaurants much more. Indian restaurants in particular would commonly cater to a post-pub crowd, but being unlicensed they would invite people to bring a few cans or bottles from the off-license or supermarket, sometimes in return for a small corkage fee.

Some etymologists believe the term has deeper roots. It has been suggested that in the early 19th century BYOB was society slang for “Bring Your Own Basket” at picnics. Even here, “basket” could well have been a polite euphemism for “booze,” but there is no evidence to suggest that this was the main implication.

In the United States, “BYOB” are four letters that warm the hearts of beer lovers everywhere. While it would be considered churlish to suggest that you “BYOB” to a party, BYOB is considered by many to mean “have yourself a royal banquet” when it’s allowed at a restaurant. The American restaurant-goer tends to blanche at lack of choice rather than undue expense. Until recently very few restaurants had decent beer lists, and other than bringing the doggie bag home, bringing your own bottle might be the only way to experience a restaurant’s food with an interesting beer. While the advent of well-rounded restaurant beer lists is wonderful for beer enthusiasts and neophytes alike, bringing your own remains a special thrill. In many cities, the invitation is usually temporary (and often technically illegal, depending on local laws). Once the establishment has its own license, the cheery notes telling you to indulge yourself tend to disappear pretty fast. In New York City, a place that has long been home to a large south Asian population, “Indian restaurant rows” were among the first incubators for shops carrying a then-bewildering variety of beer. Even in the early 1980s, well before American craft beer became prevalent, shops at either end of one block of New York City’s East Village displayed signs declaring “More than 100 varieties of beer!” What most patrons didn’t know was that most of the restaurants on the block in question were run by Pakistani Muslims, and this is why the restaurants offered no alcoholic beverages. The then-rare availability of India pale ale right alongside tasty “Indian” food turns out to have been a happy coincidence.