Yes, this is a bit gruesome. It is about Romans, what did you expect?
As regular readers probably know, the cult of the goddess, Cybele, was something of a safe space for trans women in the Roman Empire. Anyone assigned male at birth and wanting to live as a woman could join the cult as a gallus, and get genital surgery in the process (generally just removal of the testicles which was simpler and safer than taking everything). You lost a huge amount legal rights and social prestige, but trans people have always made those trade-offs.
Cybele, being a goddess of the wild places with connections to the Greek Gaia, and also with connections stretching back to Inanna and Ishtar, was very much associated with spring. There were a whole lot of celebrations around this time of year, including what amounted to a massive pride parade through Romne. But today, March 24th, was the Day of Blood — the day on which new recruits to the cult got their surgery. And thanks to dear old Claudius it became a public holiday. So we should all celebrate.
Personally I have got a nice piece of venison from my favourite butcher, and will have a glass or two of red wine. Your mileage may vary.