Spit seals the deal!

In 1922, a man named Sir James George Frazer wrote a book called The Golden Bough. It was full of notes about magic and mythology. Here's an interesting section on spit:

Spit is part of the man, and whatever is done to the spit will have a corresponding effect on him. A Chilote Indian, who has gathered up the spit of an enemy, will put it in a potato, and hang the potato in the smoke, uttering certain spells as he does so in the belief that his foe will waste away as the potato dries in the smoke.

In the Sandwich Islands, chiefs were followed by a servant with a spittoon. All day, the chief would spit into it, and the total amount was carefully buried every morning to put it out of the reach of sorcerers.

When the Wajagga of East Africa desire to make a deal, the two parties will sit down with a bowl of milk between them. Then they each take a mouthful of the milk or beer and spit it into the other’s mouth. This seals the deal.