How interesting. From “Grimoires, a History of Magic Books” by Owen Davies.
The runic farting spell found in a seventeenth-century galdrabok or grimoire that had evidently passed through several generations. It instructed the reader to write a series of runic symbols in blood on white calfskin,
"which are to 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. May you become as weak as the Wend, Loki, who was snared by all the gods. In your mightiest name Lord God, Spirit, Creator, Oðinn, þor, Savior, Freyr, Freyja, Oper, Satan, Beelzebub, helper, mighty God, you who protect your followers Uteos, Morss, Nokte, Vitales.
In 1656 Jon Jonsson, who was burned to death for sorcery along with his father, admitted carving such farting runes and sending them to a girl.
Of course the runes used were never specified, Anyone can to speculate on what ones to use in order to get the “Farting Runes” effect?