A tilberi is the freakiest creature in Icelandic folklore witchcraft. It is a small parasite made from a human rib and is designed to steal milk from your neighbors sheep and cows. It is perhaps a freakier idea than Icelandic necropants.
If you are a woman, you can try making one yourself. What you do is you take a human rib, wrap it in wool and stick it between your breast. Then you have to go to church several times, sip the holy wine and spit it between your breast. This will bring the creature to life. The next step is to carve out a nipple on your thigh and hang the tilberi onto the nipple to let it nurse. Once the tilberi is fully grown, you can release it and order it to suck the milk out of your neighbors animals. It will then return home and say “Fullur beli mamma” or “Full belly momma” and you can say back “Láttu þá lossa sonur” or “Let it guss son” and he’ll spew the stolen milk wherever you’d like.
The problem with a tilberi is that once you get old, the tilberi will literally suck the life out of your thigh. The trick to get rid of it according to some is to order it to gather all the sheep droppings of three highland pastures. This will be too much for the old tilberi and it will explode, leaving only a human rib.
If you ever think your being served “tilberasmjör” or “butter made from tilbera milk” you can make a cross mark in the butter and it should turn into foam.
Be careful though about keeping the tilberi hidden under your skirt, because an Icelandic woman in 1580 was burnt at a stake for creating a tilberi.