According to this site, the word came from Tana Mongeau in 2021. However, it could also be argued that "ong" could have originated way before then. Possibly, it could have been used by early Christians in an attempt to shorten their respect for God. Unfortunately, this cannot be proven now as they're long dead. The word "ong" is used mostly to abbreviate "on God" or "for reals".

Credits:

https://www.wikihow.com/What-Does-ONG-Mean 

https://selfdevelopmentjourney.com/what-does-ong-mean-in-texting/ 

https://english-grammar-lessons.com/ong-meaning/ 

Jordan is the biggest bum at Sacramento City College, he's majoring in engineering.