UK slang, gang related / region specific:
Endeering term used for friends with business links, particularly in a few specific areas such as Streatham (blue town), Tottenham, and Cambridge. Used in place of "blud". Can get you in trouble around Woolwich and Hackney
"wassup blue, you got work?"
"yes blue, there's at least 5 for you to work, more if you can get some p's"