When you text SIXFLAGS to 711711, you’ll receive a coupon to get a free Slurpee at 7 Eleven stores. The coupon is only good for Medium size Slurpees. You’ll need to be close to a 7 Eleven because the coupon is only good for 15 minutes. If you haven’t downloaded the 7-Eleven app, you should. You will score freebies and deals throughout the month using it.