Advent
Advent
[Cueball is looking at a large wall subdivided into a rectangular 20 x 12 grid, with each grid subdivided into 10x7 small drawers. Below the frame there is a caption:] Unsettling gift: Life expectancy Advent calendar

An Advent calendar is usually a means of celebrating the days before Christmas. Each day on the calendar is represented by a "door" (a flap of card), behind which is usually a picture related to the Christian nativity, a picture of commercial Christmas (e.g. a present), a small chocolate, or a small gift. This comic satirizes the concept by proposing such a calendar that would have one gift for each day one is anticipated to live. Such a calendar would be very morbid and existential. This is especially disturbing when given as a gift because it implies someone has put extensive thought into when the recipient will die.
In Cueball's case, assuming each square in the calendar represents one day, the wall he is facing is the entire present he received and the boxes just out of view follow the same pattern, the entire wall represents 16,800 days (a large grid of 12x20 smaller grids of 10x7 boxes: 12×20×10×7 = 16,800), i.e. just under 46 more years (16,800/365.25 = 45.99589).
Assuming that Cueball is a male from the US and the grid represents his life expectancy, according to American Official Social Security Actuarial Life Table for males, he is probably 31.9 years old . This would make Cueball almost exactly one year older than Randall , who was born October 17, 1984 making him 30.9 years old when he wrote this comic. Due to the non-linear shape of the mortality curve, the chance of Cueball making it to the end of his calendar is 57.7%, at which point he will need to get another calendar but with only 9.2 years worth of doors.
The title text refers back to a standard advent calendar by saying that the Christmases are specially marked; on a traditional Advent calendar, only the 1st to the 24th of December have doors, however in recent times, Advent calendars often also include an additional door for the day after Advent, Christmas Day. A few dozen may be any small number of dozens, and 3 5/6 dozens (46) is aptly described by a few dozen ; see 1070: Words for Small Sets . Any dictionary (for example Oxford Learner's Dictionaries ) says that a dozen may be an approximate number, not exactly 12.
A completely different advent calendar was mentioned in 994: Advent Calendar .
Similar calendars have been mentioned in the blog Wait But Why in the 2014 post Your Life in Weeks , and in equally geeky webcomic Abstruse Goose , in the 2008 post 936 Little Blobs .
[Cueball is looking at a large wall subdivided into a rectangular 20 x 12 grid, with each grid subdivided into 10x7 small drawers. Below the frame there is a caption:] Unsettling gift: Life expectancy Advent calendar
