Today is July 11 and 7-Eleven convenience stores are celebrating a big birthday. As the store chain turns 85 today, they're giving away free Slurpees to their customers and Six Flags theme parks are partnering to offer admission for $7.11.

7-Eleven Slurpee partner, Six Flags is joining in the birthday celebration and offering a special admission price of $7.11 to guests after 7:11 p.m. on 7-Eleven Day when they present a receipt from a 7-Eleven purchase dated 7/11/12. Guests who participate in this promotion will also get a VIP wristband to attend the special  "Exclusive 7-Eleven Coasters After Dark" event on Wednesday.

To find a Six Flags location, visit www.sixflags.com and call the location to find out more details and to see if they are participating.

To celebrate their 85th anniversary, from 11 a.m. until 7 p.m on July 11, 7-Eleven will be giving out free 7.11-oz. Slurpees. Not only is it the store's birthday, but the iconic frozen Slurpee itself turns 45 today and the stores plan to give out around seven million for free this year, a whole five million more than last year. The store has been doing this promotion since 2002.

To prepare for the occasion, almost all 7-Eleven stores stock up with at least 1,000 extra cups and three extra barrels of Slurpee mix. Extra employees are also on duty today to help serve customers who will be waiting on lines going out the door at many locations.

Some flavors to choose from, depending on the location, are watermelon lime, Mountain Dew, strawberry banana, lemon creme, Dr. Pepper, Coca Cola, white cherry, and pina colada.

"7-Eleven Day, or free Slurpee Day, gets bigger and more popular every year," said Joe DePinto, 7-Eleven president and CEO. "The day is also when we do something special to thank customers for their support and welcome new guests."

To find stores near you, check out the 7-Eleven's store locator. Try to call the store nearest you to find out if they're participating in the promotion. Every purchase made at 7-Eleven stores qualifies people for the Six Flags $7.11 admission.