(CNN) -- Denny's restaurants served about 2 million free Grand Slam breakfasts during its eight-hour promotional giveaway on Tuesday, the company reported Wednesday.

Cooks fill the pass-through window with Grand Slam breakfasts Tuesday at a Denny's in Emeryville, California.

The company used a commercial during the third quarter of Sunday's Super Bowl to announce it would give away its signature breakfast from 6 a.m. to 2 p.m. Tuesday, and the response was spectacular.

Media outlets across North America reported lines of customers stretching outside and around restaurants and strangers crowding together into booths to take advantage of the special.

The restaurant chain's approximately 1,500 stores served an average of 130 Grand Slams per hour to customers who waited an average of 60 minutes for their free pancakes, eggs, bacon and sausage, the company said.

"We had an extraordinary day," Denny's CEO Nelson Marchioli said when the promotion was over. "We were hoping to reconnect with millions of Americans today, and we did.

"We have received the most heartwarming comments from our servers, our managers and above all our customers. This Free Slam Day has exceeded our expectations in every way." iReport.com: Miami customers line up for Denny's meal

Denny's doesn't disclose specific cost information, but including the cost of the food, the Super Bowl spot and other production costs, the promotion cost the company roughly $5 million, it said.

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The Grand Slam started as a baseball-related promotion in Atlanta, Georgia, in the mid-1970s and has been served chainwide since 1977. Its normal price varies by market but averages around $5.99. Denny's said it sells 12.5 million Grand Slams a year.

At the normal average price of $5.99, Denny's gave away meals Tuesday with a retail value of $11.9 million. But the goodwill value could be priceless. iReport.com: Vouchers run out at Georgia Denny's

"The key is to get the guest to come back," Troy Morgan, a Denny's franchisee in Sacramento, California, told CNN affiliate KCRA-TV.

"So, we show them great hospitality and we're confident we're going to win guests and get them to return again and again."

A Denny's competitor, IHOP, is planning its own giveaway. The chain promises to give a short stack of three pancakes to all comers on "National Pancake Day," February 24. IHOP requests a donation to Children's Miracle Network or other local charities in exchange.

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