They are called fretrúnir (“fart runes”) and they were used by people in Iceland against their enemies, friends, bitchy ex-girlfriends and ex-boyfriends, rich grandparents who refused to die and everyone else whose stomachs they wanted to upset.
They were runes that “afflict your belly with great shitting and shooting pains and 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.” There is one recorded case from 1654 where a man was burnt at the stake after admitting casting Fretrúnir on a local girl. What a wonderful tradition! It’s a shame those young people just stand around in their ugly Yeezys, stare at their phones all day and don’t appreciate the old ways anymore. Speaking of Yeezys, can someone please cast Fretrúnir on Kanye West?
Read more about the runes here including detailed instructions on how to cast the spell.