The BG Special is the act of going to a movie theatre with the intention of watching several movies using only a single ticket. The BG special involves planning your trip so that you can sneak from screening to screening and watch multiple movies back to back in one visit.
The term was popularized by well-known YouTube gamer, BrokenGamezHD aka BG who often brags about theft and other fraudulent activities.
Guy 1: I saw Mad Max, Avengers and Ted 2 last night it was lit!
Guy 2: Using the BG Special again huh? Damn teach me B.
BG-Unit means "Bulgarian Unit." It is commonly used by Bulgarians who think they are awesome, thug, and cool like the actual members of G-Unit. However, the term was actually coined by two Americans, even though many Bulgarians refuse to believe this for fear that it might cause their masculinity to be questioned.
"DA JIVE VELIKA BULGARIA! BG-Unit!", said the Bulgarian, unaware that BG-Unit does not actually exist.