Haha! He should have stuck with "OMAHA, OMAHA, OMAHA!!!" I was waiting for it but didn't here it once. And as much attention as that particular audible call received in the last few weeks, I was a little surprised the announcers didn't recognize it during the game as well.
I think Peyton explained it as something more or less akin to “HUT!”. The offense would know which occurrence (first, second, third, ...) was the hike signal. The idea was to use the first call on non-critical downs (e.g, 2nd and 6 on your forty in the first quarter) and save the trickery for situations where it could make a difference (e. g., third and four on the opponent’s 11 in the fourth quarter).