The dwarven festival of the new year is three fold and celebrates all things that make Dwarf Fortress great.
First: the feast of plump helmets, only plump helmets will be eaten only plump helmet wine will be drunk. Those who complain of the same old booze, food, or otherwise slander the glorious plump helmet will be dropped into the caverns and will not be allowed to return until they fill a specially designated stockpile with one hundred gathered plump helmets.
Second the parade of dorfiness: all hands will be given picks and a section 5x10 and 5 z levels deep will be designated for channeling the miners stupid enough to severely injure themselves by digging the ground out from under their own feet will be given gifts of fine socks and will spend the rest of the festival being hand fed plump helmets by the slanderers.
And third: the crucible of insanity, spectators will watch from a window while feats of various ridiculousness occur in an arena, four dogs will fight a bear, a child will fight two crundles, one hundred kittens will fight a goblin, a man will fight a horse, and then when it can become no more insane we will send the military to the center of the arena unblock the way to the circus and dwarves will fight clowns.
If your celebration doesn't end the world you aren't doing it right.