The Game to Justin Bieber Don't Be an Idiot ... GET A WEED CARD

1/7/2013 3:15 PM PST

The Game
has some friendly words of advice from one pot smoker to another -- telling Justin Bieber ... it's time he got smart about smoking pot ... and acquired a medical marijuana card.

Game -- a self-proclaimed weed enthusiast -- was getting his hike on in L.A. today when we asked about the Bieber pics, and Game replied, "Let's keep it real. There's a lot of people in high positions ... who smoke a little weed sometimes."

Game added, "I'm not saying it's okay ... but [Bieber] made a mistake. Forgive him. Let him go through the growing pains of his life."

And if Bieber REALLY needs to smoke out -- Game says it might be worth looking into getting a prescription ... for his glaucoma ... or insomnia ... or whatever else he can pull out of his ass on the fly.