They say there's no such thing as a free lunch but for one day in America there was a free breakfast thanks to a promotion by Denny's restaurants.

Denny's, which has its headquarters in Spartanburg, S.C., announced during its Super Bowl commercial Sunday that it would offer a free Grand Slam breakfast to whoever wanted one between 6 a.m. and 2 p.m. Tuesday at any of its 1,500 U.S. restaurants.

The company anticipated up to 2 million people would take it up on its offer for a free Grand Slam, which has been around since 1977 and includes two pancakes, eggs, bacon strips and sausage links.

"The Grand Slam has always been a Denny's favorite," company Chief Executive Officer Nelson Marchioli said in a statement on Denny's Web site. "This free offer is our way of re-acquainting America with Denny's real breakfast and with the Denny's brand."

CNN reported the freebie was proving popular Tuesday, with patrons lining up outside to get in packed restaurants in many locations.

"You couldn't beat it. I mean it was a beautiful, beautiful breakfast. It was fit for a queen or a king," Annah Shoffner told CNN affiliate WNCN-TV in Raleigh, N.C.

"To do this is amazing and not something you hear of every day, especially in today's economy -- that we're getting something free," Debbie Brugger of Essex Junction, Vt., who stopped at a Denny's in Burlington, told CNN affiliate WCAX-TV.