Bloody Night

Bloody Night was something of a tradition among pirates in the later days of the Third Golden Age of Piracy. This was a celebration of pirates who had come before, praising old Captains and crewmates and telling tales of those who had become legend. Some version of Bloody Night is still celebrated by some Witches who have modified it into a celebration of their God, Thorn. There is some debate over if this began due to the association that Thorn is the God of pirates, or due to the myth stating that they had once been a pirate.
In the historical version of Bloody Night, pirates would gather together, either at a tavern or aboard their own ships when they were too far from any station. They would, for the most part, simply drink, tell stories, sing and dance. This is, arguably, not exactly significantly different from what they would do on many other nights of the year. The difference here was mainly in that their stories focused on the great deeds of other pirates, rather than themselves.
In the modern version of Bloody Night, Witches will gather together and engage in a very similar amount of drinking, singing and dancing as the historical version. The difference primarily lies in the stories that are told. The Witches will speak only of Thorn and their supposed deeds. Different legends of how Thorn came to be, tales of how Thorn saved this person or that, stories of how many people Thorn had killed.
It is also not unheard of for these modern celebrations to include some form of cannibalism. One of the many things Thorn is known for is eating the flesh of humans, and Witches have been known to emulate that in extreme cases. It is by no means common. I only mention it to avoid deceiving you. When I attended one of these celebrations and witnessed one Witch chop off two of her friend's toes, only for both Witches to then eat one. They were the only ones I saw doing such a thing, and no one around me seemed to find it at all odd.
I feel that I can reasonably assume that the historical version of Bloody Night involved much less cannibalism. If this tradition had been started during the time when the Siren of the Void (a known cannibal pirate Captain) was sailing, however, I would be much less sure of that fact.