If you have a 7-Eleven store nearby, make sure to stop by tomorrow and get yourself a free slurpee.

The convenience store turns 79 years old tomorrow (on 7-11), making it the world's oldest convenience store chain. To celebrate, they're offering free slurpees, in special "happy birthday", 7.11 ounce cups, for as long as the cups last.

In addition, it's also the 25th anniversary of the company's "Big Gulp" fountain drinks. They were originally 32 ounce cups when they first launched in 1981. To commemorate, all 7-Eleven stores are offering special 40 ounce cups for the price of a 32 ounce cup, giving you 25% free beverage. The offer lasts all summer long.

7-Eleven was the first convenience store to advertise on television, operate 24 hours a day, sell gasoline, offer fresh-brewed coffee to-go, self-serve fountain drinks and giant drink cups, and sell pre-paid phone cards.