It is generally believed to relate to the traditional student song, "De Brevitate Vitae" (On the Shortness of Life), which is commonly known as the Gaudeamus (Let's make merry) by its first word.
These evenings are followed by Raisin Monday which is used by the junior students to thank the academic parents (usually in a ritualised fashion) for gaudie night.
St Andrews has a separate ceremony known as the gaudie which involves a gowned torchlight procession and singing of the Gaudeamus in memory of a student, John Honey who risked his life in 1800 to save survivors of a shipping accident offshore.
[3] The Lord Peter Wimsey mystery Gaudy Night, by Dorothy Sayers, is partly set at such a reunion at a fictional women's college at Oxford.
The Gaudy (1974), set in an unnamed Oxford college, is the first novel in the A Staircase in Surrey quintet by J. I. M. Stewart.