Loki

"Of course", said Loki. "You can, of course, cut off my head. But—and I appeal to mighty Odin here—if you cut off any of my neck, you are violating the terms of our agreement, which promised you my head, and my head only."
Odin inclined his ehad. "Loki is right," he said. "You have no right to cut his neck."
Brokk was irritated. "But I can't cut off his head without cutting his neck," he said.
Loki looked pleased with himsel. "You see," he said, "if people thought through the exactness of their words they would not dare to take on Loki, the wisest, the cleverest, the trickiest, the most intelligence, the best-looking . . ."
Brokk whispered a suggestion to odin. "That would be fair," agreed Odin,
Brokk produced a strip of leather and a knife. He wrapped the leather around Loki's mouth. Brokk tried to piece the leather with the tip of the knifeblade.
"It's not working, said Brokk. "My knife isn't cutting you."
"I might have wisely arranged for protection from knifeblades," said Loki modestly. "Just in case the whole you-can't-cut-my-neck ploy did not work. I am afraid no knifeblade can cut me!"
Brokk grunted and produced an awl, a pointed spike used in leatherwork, and he jabbed it through the leather, punching holes through Loki's lips. Then he took a strong thread and he sewed Loki's lips together with it.
Brokk walked away, leaving Loki with his mouth sewn up tight, unable to complain.
For Loki, the pain of being unable to talk hurt even more than the pain of having his lips stitched into the leather.