I am absolutely in love with this game for some reason, despite the fact that there doesn't seem to be a whole lot of content included with the game. 

Sadly, the same thing cannot be said for the community -- and not because I don't like your attitudes. As a matter of fact, I've come to find that the Mafia Returns community is among some of the friendliest I've encountered in all my years of internet gaming.

What it is that grinds my gears, are these goddamn abbreviations. BL, BG, HC, CL, so on and so forth. 

Would anyone mind breaking these down for me? Thanks. :D

BG = Bodyguard

CL = Crew Leader

Not sure I know of the others :)

I'm as bad as anyone for using acronyms, but a few of those have me pretty stumped. 

BL? Not a clue.

HC? Can be used to refer to "Hitter Channel" on IRC, but a relatively rare one and would be very dependant on context.

If someone using an acronym you don't know in general conversation, simply ask them. Some of the terms are used so frequently (BG = Bodyguard, CL = Crewleader, RHM = Right Hand Man, JB = Jailbreak, WB = Wackback, etc.) that users don't even think twice about throwing them out there in conversations.

If it's included in a headquarters (HQ) thread, point out to the crewleader (CL) in question that there are shorthand acronym's being used without first explaining what the acronym stands for. They should be delighted with the feedback and having the opportunity to improve things for other new players. 

...as far as I know, HC & BL are just texting abbreviations. 

HC is Holy Cow

BL is Bad Luck or Bottom Line

HC = Home City.

BL = Bloodline.

At least that is what I would assume them to mean in an in game (IG) context ;)

I think the point here is - given the lack of clarity, it would be perfectly acceptable to ask the question of whoever is throwing the abbreviations in your direction.