A short for Ol' G-sus also known as Old Jesus, Jesus christ or Old dawg Jesus. To use when you feel blessed.
I just won the lottery, it must be the OG!
My Mama Diane is the OG. Growing up she showed her love and care for me by incessantly correcting my grammar.
OG or "The Original Gangsta" is someone who's been at it longer than anyone, is incredibly exceptional and authentic. A high ranking member.
Yeah, Brittny is an OG. She taught me eveything I know!