Gang signs in sports -- The Paul Pierce incident

The NFL is reviewing footage in search of "gang signs" as a reaction to Paul Pierce's "menacing gesture" during an Atlanta Hawks game, according to this LA Times article.

"There have been some suspected things we've seen," said Milt Ahlerich, the league's vice president of security. "When we see it, we quietly jump on it immediately, directly with the team and the player or employee involved to cease and desist. Period."

Here is the YouTube of the alleged gesture:

Here's Paul's side of the story:

Supposedly it is not a symbol for "Bloods" but rather for "blood, sweat, and tears," the reporter claims.