Yeah, as has been said, it's a misinformed throwback to straight edge culture. The X on the back of the hand is a straight edge symbol and has become integrated into the culture of hardcore punk, resulting in many bands prefixing and suffixing their band names with X, such as xDEATHSTARx or xSTRAIGHT DOWNx. Cue borderline retarded emo kiddies who see this, comeletely misinterpret the use of the X without the positive ideals inherent in the straight edge connotations and use it ad nauseum for their shitty little gamertags.