n. A typically overpriced, small amount of mid quality danknessMarijuana that can be purchased within the suburbs of Oak Park, California. The price of an Oak Park Gram typically hovers above or at $20 USD and can be purchased in obvious consumer locations such as 7-11.
"Yo dude think anyone in your phonebook can hook us up with some herb?! I'm dying for an Oak Park Gram!"
"Don't sweat it, I know tons of kids slinging OPG's, just hit up 7-11."