In Snoop’s song Pump Pump, there is a line:
Just trying to find out what a “BG” is. Sledman works with a guy who goes by BG and thinks of the song everytime the guy calls.
BG stands for Baby Gangster, which is similar to rookie: a young, new member of the gang who doesn’t garner much respect yet.
The polar opposite of OG: Original Gangster, an esteemed older member (usually anybody over 25 or so).
Cool. Thanks, hapaXL!