The freebie runs from 11 AM to 7 PM at participating 7-Eleven stores in the US and Canada. They'll be giving out free small Slurpees (12 fl oz) during that time period.
If you're hoping to try some new flavors, the most recently added flavors include the aforementioned Birthday Cake as well as Sour Patch Redberry and Sugar-Free Pineapple Mango.
Image via 7-Eleven.