It is an ancient troll tradition -- one of the few that doesn't involve murdering each other -- to gather behemoth leavings at the turn of the sweep, to celebrate the end of an old year and the start of a new one. The Milliways trolls have divided the tasks between them; Karkat and Kanaya
hunting a behemoth leaving, and Nepeta agreeing to stay behind and hunt for materials to decorate it.
Maybe Nepeta's hunt wasn't as dramatic as Karkat and Kanaya's -- and oh, is she ever going to paint that story -- but it was definitely as successful, and she's had some time in her cave to put some of her findings together into proper Twelfth Perigee's Eve decorations. Not all of them, though, which is why when she enters the bar by way of the rear door, she is carrying an enormous heap of assorted ... stuff. Strips of furry and scaly hide, feathers in bunches, things that might be claws, a few evergreen branches, and quite a lot of less identifiable things. Captchaloguing all of this might have been smart, but she's not sure she could find it all again.
Meanwhile Karkat has finished nailing the antlers they brought back to a crosspiece (accomplished while Kanaya was messaging Nepeta to come) and is now putting on the first round of decorations; he is (trying to) top each projection of the antlers with a candle. Since the antlers are twice as long as he is tall and a little higher than the top of his head, he may need the box Kanaya's holding off to one side patiently, waiting for him to give up. Periodically he equips his megaphone and invites the bar proper to an exceedingly multicultural fucking experience.
Anyone want to come have one? Drape a few chains of bird claws or demon bunny teeth over the antlers, or use the crayons and paper to make some slightly more human-friendly decorations. Or feel free to just stand there. And watch.