Called fretrúnir, literally “fart runes”, they were used by witches in Iceland against their enemies. They were runes that “afflict your belly with great shitting & shooting pains & all these may afflict your belly with very great farting. May your bones split asunder, may your guts burst, may your farting never stop, neither day nor night.”
And if that’s not weird enough, in the Holmavik Museum of Sorcery and Witchcraft in Iceland, there’s a pair of necropants. What are necropants? I’m glad you asked. They’re a pair of pants, made from the skin of the lower half of a dead person. When worn, these pants would produce money as long as a coin stolen from a poor widow was placed in the scrotum. Ta da!