Crossing the Equator
There is an ancient ceremony associated with crossing the Equator. It is an elaborate "play" with actors and costumes and some ritualistic hazing thrown in for luck. I'm not going to describe everything that is going on here since there are better sources for that elsewhere, but I'll try to cover the basics.
To start with, there are two groups of people: Shellbacks (those who have crossed before) and Tadpoles (those who haven't). The night before the ship crosses the Equator, the Herald arrives with the Royal Court and summons the "Subbie's Guard" for inspection. Invariably, the inspection does not go well, and the ship's company is told to prepare for King Neptune's arrival the next day. The ship's company splits into two groups (Shellbacks and Tadpoles) and an orgy of drunken violence takes place.
The next day starts off with the "Tadpole's Breakfast", followed by an initiation ceremony later in the day which included getting fish guts smeared on your face, eating a "medical pill", getting "shaved" and then hopefully getting dunked in the pool. After that, the new Shellback emerges to the chants of "Clean!" and he is no initiated. The full Royal Court with all its players as well as the "Bears" and "Police" ensure full participation.
A video is also available:
But once the Bears dunk you, you are no longer a Lowly Tadpole but a Trusted Shellback. Then it's all over, and eventually you will be issued a card (don't lose it!) that will forever identify you as a Shellback.
Well, it's not as bad as it looks. On this trip everyone participated except 4 people, 2 of whom had already completed the trials, but had forgotten their card at home.