Bachelor party
A fire dance at Jadzia Dax's bachelorette party
A bachelor party is a celebration of a bachelor's last days before marriage. Its female equivalent was a bachelorette party.
After the Dax symbiont had been transferred to him, Verad Dax recalled Benjamin Sisko's bachelor party, parts of it, at least. (DS9: "Invasive Procedures")
In 2374, a Klingon ritual known as the kal'Hyah was held for Worf by General Martok in a Deep Space 9 holosuite. Benjamin Sisko, Miles O'Brien, Julian Bashir, and Alexander Rozhenko attended, under the mistaken impression that the ritual would be the equivalent of a four-day Human bachelor party. (DS9: "You Are Cordially Invited")
In 2375, Benjamin Sisko asked his son Jake to be his best man at his wedding to Kasidy Yates. The younger Sisko noted that his responsibilities would include planning a bachelor party. (DS9: "Penumbra")
In 2374, Jadzia Dax had a bachelorette party prior to her marriage to Worf. (DS9: "You Are Cordially Invited")