Through July 31st from 4PM-8 PM daily, head in to 7-Eleven where you can grab 50% off Slurpees and/or Big Gulps when you scan your 7-Eleven Rewards app (free to download and join).
Note that participation may vary so call your local store before you make an extra special trip. I did this deal on 6/29 and it worked- when they scanned my app it took 50% off the price.
If you don’t already have the app you should get it- every 7th drink is FREE!