DALLAS - On Sunday, 7-Eleven, Inc., will give customers a free 7.11-ounce Slurpee to celebrate 7-Eleven Day. The convenience retailer celebrates its 83rd birthday this July 11.

Participating 7-Eleven stores across America and Canada will serve 5 million free Slurpee frozen carbonated beverages in special birthday cups on Sunday while supplies last. "Slurpee-brations" and 7-Eleven birthday parties are being held around the country with music, entertainment, prizes and food sampling. The convenience chain has been celebrating its birthday with free Slurpee drinks since its 75th anniversary celebration in 2002.

7-Eleven is also using its namesake day to kick off its second annual Slurpee Battle of the Bands (BOTB) contest. Starting this Sunday, a dozen home-grown musical groups will begin showcasing their talents and compete for semi-finalist status at four regional concerts.

The first concert takes place Sunday, July 11, at 7 p.m. in Los Angeles at The House of Blues on Sunset Strip where three of the bands will open for a performance by Train, the Grammy Award-winning mainstream rock group from San Francisco. In this virtual talent contest, fans can view all performances live online on Slurpee??s Facebook fanpage and vote for their favorite band at Slurpee.com. Voting is open for three days immediately after each event.

"7-Eleven Day has become so popular that people mark it as a recurring event on their calendars," said Stefanie Olson, 7-Eleven brand manager for Slurpee and Big Gulp beverages, in a press release. "Some people forget that it??s July 11th or 7-Eleven Day. They just know it as free Slurpee day. It??s a great way to create a party atmosphere at our stores. Everyone wants to celebrate!"

Free Slurpee drinks aside, July, typically the hottest month in the United States, is the top-selling Slurpee month of the year.