That guy is a jerk, between making gang symbols and beating his gf i wouldnt want a picture of him! altho he is such a beast fantasy wise...
Umm, I think you got your facts wrong on the reason why he does that.Here's a link on the explanation:
The "Diamond Cutter," or "Flashing the Roc" as it also is called, has become the symbolic gesture for anyone associated with the clothing line Team Roc, which has an endorsement deal with Johnson.
The gesture itself - holding both thumbs and index fingers together to form a diamond shape - is embroiled in controversy because Team Roc's founder Jay-Z is being sued for copyright infringement for using the symbol (a wrestler claims he was the first to use the symbol in the 1990s.) As for the NFL, it already has a business relationship with Nike and Reebok, both of whom happen to be on Team Roc's list of competitors. Reebok makes the NFL's uniforms, while both Nike and Reebok have shoe licensing deals with the league. That might make Johnson's "Diamond Cutter" gesture a conflict of interest with the league, sort of like wearing an insignia other than Reebok or Nike. As of now, the league is taking no action.
Also, I think he does it since he always used to call himself a diamond in the rough.
Nothing to do with gangs.