What does Kublai Khan mean?

The sentence "You must XX" which is popular in the comment area recently is called the blessing of the underworld. It makes people laugh because they also use the sentence pattern that X must X, but it doesn't really mean anything.

Boljijin Kublai Khan, Torre's fourth son, a state supervisor, was a Mongolian politician and strategist in Yuan Xianzong. He was the first emperor of the Yuan Dynasty and was honored as "Snow Zen Khan" in Mongolia. Kublai Khan is famous for his filial piety. He was familiar with China culture, and appointed Han Confucian scholars to rectify official administration and military and political affairs. His brother Mungo succeeded to the throne and became Yuan Xianzong, and Kublai Khan got a fief in Jing Zhao. In the same year, he led the army to destroy Dali, and then cut the Song Dynasty with Mongolia.