Any of you X's and O's afficienados care to enlighten me as to why most NFL quarterbacks shout out "Blue 18!" or "Green 80!" Or combinations of those two at the line of scrimmage? There are many others of course but those two seem to be the most ubiqitous. At first I thought it was just Seahawks quarterbacks (the blue and green designations make sense) but for years now I've heard nearly every QB in the league shout those out at the line.