[1] - First go here: https://www.sonicdrivein.com/

[2] - Sign up with your catchalls! ( you can use temporary mail if you want )

[3] - Once you're signed in to your new account, you'll be prompt with your rewards, there'll be 2 rewards, but the one you want to choose is the "Free cheeseburger with purchase"

[4] - Once you add it to your bag, click on "Thirsty?" underneath your Free cheeseburger food item.

[5] - Then just scroll down click on "other" and scroll to "water" and add it to your bag.

[6] - Now head over to your bag and make sure you add a Sonic Drive in restaurant location near you and then click checkout! Should be about 50 cents, cheap burger and some water.

[7] - Rinse and Repeat!