When the quarterback crosses the line of scrimmage and places his hands beneath the center, he yells "Set" (which causes the linemen to drop into their stances) and then something along the lines of "Green 80, Green 80, Hut-Hut." On the second "Hut," the center snaps the ball. In this scenario, "Green 80" has no meaning. It's just a way for the quarterback to tell his teammates that they are in a huddle. The quarterback will also sometimes yell "Hut" or "Hurry" as a call for an immediate handoff instead of a drop back pass. This is most common after a change of possession during goal-line situations or late in games when time is running out. Finally, if the quarterback feels like he has been hit while he is under center, he can signal for a "false start" by yelling "False!" While this is not common, it does happen from time to time. If this call is heard, the referee will stop the game and issue a false start penalty against the offense. As you can see, there are several ways for a quarterback to communicate with his offensive team members. Although these are the most common calls, there are other ways used by great quarterbacks that may not be apparent from watching them play because they are usually called from the sidelines by head coaches or offensive staff members.