There are free fireworks in the Garden Gazebo to celebrate New Year’s! There is a huge crate near the wheelbarrow at Kat de Claw. Click on it and get 10 fireworks. You can click on it every 15 minutes so if you have time you can get a lot of fireworks.
You set off the fireworks by clicking them in your backpack (in the loot section) and then placing them on the ground. Then move your cursor over them and they shoot off. I think they look best when you set them off in a darker colored room like the Crystal Catacombs.
