The Tsirth of Hussik

As szassar science progressed, and their knowledge of celestial bodies increased, their astronomers began to identify other planets within their solar system. The next planet out from Szorik is known as Hussik, "the smaller child". Its precession across the skies is slower than that of Szorik and is very slightly more elliptical, but it orbits in the same plane as it's larger planetary sibling. 
A more traditional element within szassar society still celebrate a festival called the Tsirth of Hussik every time the smaller and slower moving planet is aligned with Szorik and Szor. During the Tsirth (archaic: "Blessing") children are brought to a body of water near the population centre concerned, where they are plunged into the water and taught the limits of their underwater swimming capabilities, which in the case of szass are quite extensive. Nobody is quite sure why this specific practice is aligned with the alignment of Hussik, but it remains an important and fun day out for many szassar communities, especially those that live on coastlines and the shores of rivers and lakes.*
Once the dunkings are complete, the participants in the festival participate in swimming races and other competitions, such as diving for "treasures" (treats) and diving for fish. Older participants compete for angling trophies. The festival culminates in a feast of fish and seafood, served with side dishes of spiced kelp.
In polar areas, the Tsirth of Hussik is also a time for old szassar to drink and tell tales of the mines and of the sea, depending on which specific area they live in. Such tales often have an educational element, although often from a "what not to do" perspective. They tend to involve significant hilarity and embarrassment for those featured in them, and the fact that almost everyone over the age of 100 has tales told about them acts to remind all concerned that no szassar is immune from being used as an object lesson. For a szass to take offense to an embarrassing tale is considered gauche, no matter how much the story has been embellished over the years. The socially acceptable response is "That's nothing... have you heard the one about..." followed by an even more absurdly hilarious tale about their tormentor.

* Important note: Szassar from polar climes tend to favour a quick dunking rather than an extended period underwater for obvious reasons. Whilst szassar are somewhat warm-blooded, their endurance of cold is less than mammalian species that share their world.