Jai Shri Krishna

Jai Shri Krishna (or Jai Shree Krishna) is a Hindi expression, translating as "Glory to Krishna" or "Victory to Krishna", a major deity in Hinduism. The glory expression is believed to have hailed from the Mahajans and Vaishnavites. The expression is said to greet another person wishing them full of success and has also been used as a greeting accompanied with namaste or bowing head, specially while greeting elder ones. 
Jai Shri Krishna expression is widely used expression to greet people during the Hindu festival of Janmashtmi, which celebrates the birth of Krishna. In present day, Jai Shri Krishna is widely used among the Vaishnav community, Jain community, Gujataris and Rajasthanis, based in and out of India.
Anecdotes.
In one instance in Hindu text, when demons failed to kill Krishna, Kansa thought to kill him by inviting him to Mathura. On reaching Mathura, Krishna met with one of Kansa's washerman, requesting for few dresses for his friends who have accompanied him. The soldier on learning that it is Krihna who is infront of him and that he is Kansa's undeclared enemy, tried to kill Krishna assuming he will be rewarded. Looking at the soldier's failed attempt and Krishna's strength, the crowd accumulated in market poured with slogans on Krishna and such as Jai Shri Krishna along with Jai Shri Balram and Jai Shri Vasudev, hence glorifying Krishna's brother and father respectively.
Popular culture.
There is a series with the same name aired on Colors TV between 21 July 2008 to 15 September 2009, which itself is a remake of Sri Krishna, which was aired between 1993 to 1997 in Doordarshan and was re-telecasted in 2020.
Prime Minister of India Narendra Modi during the 2020 Janmashtmi festival greeted his followers with a tweet mentioning "Jai Shri Krishna". The tweet read, "Best wishes on the auspicious occasion of Janmashtami. Jai Shri Krishna.".