SX3 means: Stockbridge Sex Slaves – Named after a group of teenage boys who were established in Stockbridge, Massachusetts in 2006. Their advanced sense of humor is well-known, as are their high tolerance for marijuana. They usually gather in trees and build elaborate tree-houses. The sign they use is a cross with their index and thumb, and three of the fingers in the air. To signal their pride in the SX, the gangster moves the fingers and cries “lololololololo”. You must undergo mild hazing to become a member. You must also be extraordinary enough to be accepted as a member. (in Community Dictionary, added by Repetend)