It means 'You Go Yuri,' a salute to Thur Krowned Head, Yurius Guderian. It is used as a greeting, thank you or as a celebration by Kingites of Thur UKK or ⟅UЖ⟆.
First usage of yugoyuri was by a member called Vigatio Osvigati in 2017 during an election in which Yurius Guderian was running.
UKK member 1: "Hi"
UKK member 2: "Yugoyuri, how are you?"
UKK member 1: "I just bought you some mcdonalds"
UKK member 2: "Yugoyuri, I am grateful"
UKK member 1: "No problem, our planned invasion of Papua New Guinea on July 8th 2050 is looking very good"
UKK member 2: "Yugoyuri, I am celebrating"