History of the tradition from https://en.wikipedia.org/wiki/Tibb’s_Eve

Tibb’s Eve is a folk expression for a day which will never arrive. A celebration held on 23 December in Newfoundland and Labrador is also known as Tibb’s/Tipp’s Eve.[1]

Tibb’s Eve was traditionally used in Newfoundland vernacular as a unspecified date that didn’t exist. If you asked someone when they were going to pay you back the money they owed you they might answer “On Tibb’s Eve” meaning that you probably won’t see that money again.[17]

Eventually, proverbial explanations arose as to when this non-existent Tibs Eve was: “Neither before nor after Christmas” was one. “Between the old year and the new” was another. Thus, the day became associated with the Christmas season.[3]

Sometime around World War II, people along the south coast of Newfoundland began to associate 23 December with the phrase ‘Tibb’s Eve’ and deemed it the first night during Advent when it was appropriate to have a drink. Advent was a sober, religious time of year and traditionally people would not drink alcohol until Christmas Day at the earliest. Tibb’s Eve emerged as an excuse to imbibe two days earlier.[9]

An outport tradition not originally celebrated in St. John’s, Tibb’s Eve was adopted circa 2010 by local bar owners, who saw it as a business opportunity.[18] Brewery taproom owners have suggested that hosting Tibb’s Eve events allow them to open up “Newfoundland experiences to outsiders.”[19]

Since then, social media and expatriate Newfoundlanders have spread the tradition to other parts of Canada, such as Halifax, Nova Scotia[23] and Toronto, Ontario.[24]

In 2019, comedian Colin Hollett described the holiday this way for a Halifax newspaper: Tibb’s Eve on December 23, when people drink and eat at kitchen parties and bars with all the people they want to celebrate with before spending time with those they have to. I have no idea how that isn’t huge everywhere else.[27]

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