So i just watched the Seahawks @ Packers and Aaron Rodgers was saying the exact same phrase at every snap...something like 3-19 and then inaudible.
It made me wonder what the QBs are calling. I always thought it was their play.
They call the play in the huddle, before coming to the line.
Some of what is shouted, while on the line & ready to go, is audibles or cues. To change the play up, after looking at the defense's setup (an "audible"). Or bringing attention to possible extra blitzers who look like they're gonna try to come after the QB.
once they're at the line of scrimmage and starting the play, it can be a mixture of changes to the play, confirmation of what's already been called, gibberish to confuse the defense, or just accented syllables to tell the center when to snap the ball.
But the Packers QB called the same thing everytime...at least initially. He'd call "3-19...3-19" c them something else immediately at the snap
A lot of the time, they are establishing a cadence to mess with the defense and attempt to draw them offside. The defense is trying to anticipate the snap of the ball and cross the line of scrimmage as the ball is snapped. The QBs try to take advantage of that.
Interesting and it sounds cool.