That is, the night that Santa's evil demon companion terrorizes small children and punishes them for their various misdeeds. It's a tradition grown from alpine folk lore, where the castigation of bad kids takes equal air time with the reward of St. Nick's gift giving during the holidays.
This involves having a creepy cloven hoofed monster loitering nearby as children sit on Santa's knee, waiting to do the dirty work of scooping the naughty ones into his barrel backpack. Then comes the beating with birch swatches and rusty chains, and the dragging you away to hell business. Watch the F out! Krampus doesn't dick around.
More and more, Krampusnacht is also becoming a night for drunken revelry, as adults adopt the guise of the demonic holiday helper and boozily parade through the town at night; no doubt frightening all the children in their wake into good behavior and inspiring hope that Santa's the one coming down your chimney.
Muahahaha...Enjoy all! I think I'll pick up some beer with a spooky label tonight to celebrate.