O.T. Genasis -- Straight Cash, Homie!!! Flashes Trunk Full o' Green (VIDEO)

This video is some "Scarface" s**t -- O.T. Genasis rolling with more dead presidents than Arlington National Cemetery, and he popped his trunk to show off the massive STACKS of cold hard cash.

The "CoCo" rapper was out Wednesday in Beverly Hills, and all we asked was how he planned to top his hit song -- and then he flashed a wad of cash in his pocket. That alone would've been impressive.

But then he walked to his Yukon (which we're dubbing the Benji Mobile) and revealed the crazy amounts of cash! Seriously, it's several hundreds of thousands.

O.T. tells us what he plans to do with the loot -- or at least, some of it. He doesn't explain how he got it. What's really insane is he only has ONE bodyguard, and he's NOT in an armored truck!

Bev Hills ain't the 'hood, but damn ...