Money B

Money B -- part of the legendary rap group Digital Underground -- says Justin Bieber might hang out with a few famous black people ... but doesn't mean he wouldn't get his ass beat in the hood. Bieber has upped his street cred quest by hanging with Rick Ross and trying to rap to 2Pac at a club ...…

Don't be shocked if another Tupac sex tape pops up because the rapper who co-starred in the first one ... says he and 'Pac used to hang out like that "all the time." Money B from Digitial Underground told a camera guy in Hollywood, he knew the tape -- shot 20 years ago -- would eventually see the…