GREEN BAY, Wis. -- Aaron Rodgers has a code word -- it's ever-changing and never shared publicly, even after the fact -- when the Green Bay Packers quarterback thinks he catches a late-substituting team with 12 men on the field.

Wouldn't the Atlanta Falcons -- and everyone else on the Packers' schedule -- love to know what it is?

Between that and Rodgers' ability to draw defenders offside with his varying snap-count cadences, the Packers are a free play waiting to happen time and again. Since 2008, when Rodgers became a starter, he has three times as many touchdown passes on free plays than any other quarterback in the league. His career regular-season total hit a dozen in the season-opening victory over the Seattle Seahawks, who got caught with an extra defender on the field and then watched Rodgers fire a 32-yard touchdown pass to Jordy Nelson on the free play.

Ex-San Francisco 49ers coach Jim Tomsula once said he had a tape "that's probably close to a game-tape long of [Rodgers] getting people offside and whipping that ball down the field."

"Free Play" Pass TDs Since 2008 Aaron Rodgers 12 Joe Flacco 4 4 others tied at 3 Defensive offsides or 12-men on the field

Joe Flacco, with four, is the only other quarterback since 2008 with more than three free-play touchdown passes.

"Having played with him, that's one of the things that excels at: catching you at every moment that you're not thinking about it," said Falcons defensive coordinator Marquand Manuel, a former NFL safety who played for the Packers in 2006. "Sometimes guys get lax, like when you see guys jump off side, he hits you with the hard count, silent count, things of that nature."

Manuel no doubt will make special mention of it to his players before Sunday's game in Atlanta. But then again, does anyone think opposing defensive coaches fail to mention it?

"I know teams prepare for that," Rodgers said.

Rodgers said he can tell as much by watching substitution patterns.

"You see guys, the play ends on a second down, they sprint to the sideline," Rodgers said. "The play ends on their side of the field and they immediately know this is when we've got to get off [the field]. And they understand the most important thing is just getting those first couple of guys off. Yeah, it's awareness, but you still have to discipline on the cadence and it's something we've used for a long time."

Aaron Rodgers excels at catching defenses off guard and has 12 touchdowns to show for it since 2008. Joe Robbins/Getty Images

It happened last year in Atlanta during the regular-season game in October, when Rodgers went into hurry-up mode because he saw defensive end Brooks Reed slowly heading toward the Falcons' sideline. Rodgers uttered whatever the code word of that day was, and sure enough, they got the snap off before Reed was off the field. That play wasn't one of the 12 free-play touchdowns because the officials didn't throw the flag on the third-down play that resulted in a short completion. However, coach Mike McCarthy challenged it, and replay confirmed Reed was not off the field in time. The penalty gave the Packers a first down that led to an eventual touchdown.

Most of the time, Rodgers goes deep on free plays. His free-play touchdowns average 30.8 yards, including Sunday's 32-yarder to Nelson. As soon as Nelson hears the word, he and the other receivers have one job: go deep.

"It's one word, we all line up and know what to do," Nelson said. "So it's worked for us multiple times over the years, it will continue to work for us. It's something that teams are prepared for now, so they've got to stay on the field. If not, we'll take advantage of it."

Even a first-time starter like right tackle Kyle Murphy, who had played a total of eight regular-season snaps before Sunday's opener, knew what to do.

"Everyone knows how cerebral Aaron is and how aware he is as far as what the defense is doing," Murphy said. "He just saw an extra guy running off the field and he gave us the word -- I'm not going to give you guys the terminology and give away all our secrets. We always know it's going to at least be a free play and we like to take those shots, and that was a pretty sweet play."

ESPN's Vaughn McClure contributed to this report.