It's a common Quick Snap cadence that has been utilized since the early/mid 2000s. Many QBs doing it. I've seen Romo and Brady use it the most off the top of my head.
When the QB yells out OMAHA OMAHA, it's letting the Center know that when he says the NEXT keyword, he should quicksnap it, disregarding whatever he said in the huddle. I know when Romo used this cadence, his keyword was "One"
So in the huddle he might say "hike on 3" or some shyt. Gets to the line and sees something he doesn't like, be it safety sneaking up or LBs playing very close to the LoS in their gaps. Decides to quick snap so they can't time their blitzes.
"OMAHA, OMAHA, OMAHA"
"ONE" - Immediate Snap
You typically see the Gs and Ts react a tad half-second late on these plays because the C is the first one to move to avoid False-Starts








