In 1860 BC, Ikūn-pî-Ištar, king of Isin in Sumer, received a very troubling prophecy: a great tragedy would befall the King, soon. So Ikūn-pî-Ištar had a genius idea: let's take some poor idiot, make him king, and then "rebel" against him and put him to death, satisfying the prophecy and leaving Ikūn-pî-Ištar unharmed. Ikūn-pî-Ištar picked the first lowly worker he found, a gardener named Enlil-bāni, and abdicated the throne in his favor. Ikūn-pî-Ištar then went off to eat a bowl of soup, which he promptly choked on and died. Enlil-bāni then refused to relinquish the throne and reigned for a relatively safe and prosperous 24 years, lowering taxes and rebuilding the city's temples and walls.
Source: History of the Ancient World by Susan Wise Bauer
It later became more popular in Assyria, but this is iirc the first recorded instance of it happening.