Icelandic children were once told to behave or they would be eaten by a pair of ogres that lived up in the hills. The characters were considered to be so terrifying that a public decree banned the use of these stories to scare children into behaving.
Instead of talking about the ogre couple, parents instead started telling stories of the ogre’s children, the Jolasveinar, who are bad, but not nearly as evil as their parents. Jolasveinars were originally said to play tricks on people and steal food, but now they are responsible for giving gifts to children. Bad children don’t get presents though, they get potatoes or other items that remind them that they weren’t forgotten, but don’t deserve real presents.