Read, if you will, the official program [in Dutch] for this year’s Dead Duck Day celebration—which will happen June 5, at the Natural History Museum in Rotterdam, The Netherlands.
Dead Duck Day honors the mallard duck that became known to science as the first (documented) ‘victim’ of homosexual necrophilia in that species. The study that documents the incident was itself honored, along with its author, with the 2003 Ig Nobel Prize for biology.
Here’s video of Kees Moeliker, who witnessed the original incident, and later wrote that scientific study, telling all about it in a TED Talk:
BONUS: Everyone who attends the Dead Duck Day celebration is invited to also join Kees Moeliker, immediately after the ceremony, for the traditional short walk to a nearby Chinese restaurant for a delicious six-course duck dinner.