So if an American kid misbehaves, he'll receive a few pieces of coal on Christmas. If a German kid misbehaves, he'll be kidnapped. And this isn't a standard kidnapping. He'll be stuffed into the bag of a half-goat half-demon monster taken to who knows where.
There are enough kids out there scared of the all knowing, chubby, white bearded dude that hands out presents once a year. Now imagine the effect a literal demon will have on children. It's definitely a very effective method of making kids behave, however they will be mentally scarred for life.
Krampus is the counterpart to St. Nicholas and originated in German folklore. Nowadays you'll be able to witness hundreds of Krampusses at the annual Krampus Run, a great way to terrify your children.