Handshaking
It was in the eighth century BC when Ashur-dan III was defecating in the royal garderobe staring down at the moat and plinking flies with pebbles from a peashooter when he heard a great commotion outside. Hastily pulling on his garments too early, as he rushed from his unfinished relief, he found his brother Shalmaneser IV in the hallway in a great furor.
“What’s wong, Shalmy?” cried Ashur-dan.
“It’s Father,” said Shalmaneser. “Adad-nirari III has died!”
This caused Ashur-dan much anguish. So much so that the rest of the pent up shit in his guts began to release. Ashur-dan immediately shoved a hand below his buttocks to stem and catch his own waste.
“What am I going to do?” continued Shalmaneser. “I so much do not want to be king. I do not wish this. Yet I am the eldest.”
And such was his distress that he almost began to faint, as was his tendency. He truly was not well suited to lead the Assyrian empire.
Without thinking, Ashur-dan the younger son reached out and caught his brother’s hand with his own scat-filled one.
Shalmaneser was so surprised by this that he immediately said, “Why have you soiled me?”
Ashur-dan was both embarrassed and chagrined by his unintended gaffe. But he had a nimble mind. “Brother,” he said, “by this act, I transfer my bodily support and full strength to your reign over our fair land.”
And thus was begun the tradition of handshaking and the origin of the phrase: You can wish in one hand and shit in the other, and see which one fills up first.