TMZ Sports caught up with The Game after the Niners beat the Green Bay Packers 37 to 20 in the NFC Championship ... and the dude was clearly pumped for his team.

Of course, Game is a die-hard fan (he even has a Niners tat) ... but he was extra stoked to boast about his smart move by putting money on the line via a "hood bet."

For those unaware of what a "hood bet" is, Game describes it as "a bet with a motherf***a from the hood that you know gon' pay the money when you done."

"You can trust him cause he from the hood and if they don't pay., they gotta deal with the street code."

Game even showed us his winnings ... and explains he's gonna put up even more money for the Super Bowl