I am a non-LDS, BYU fan married to a black woman and we have kids. Thug is a common urban slang term now, used as much in a glorifying sense as it is derogative, but it's origins date back 800 years.

It basically means common criminal, nothing less, nothing more and has been used that way throughout the 19th and 20th century against all ethnic groups. Don't twist it's common popular reference to a culture (which has nothing to do with color) into a racial issue.