The best way to get free food from chain restaurants seems to be through surveys on their receipts. Like this OP discovered, the Jack in the Box near their place would send them a link to a survey every time they bought something. Once you filled out the survey, you would three free tacos.
When you went to pick up the tacos, you would get a new receipt with a new survey code. You know what that means right? Infinite tacos! Frankly, that sounds like heaven to us. Apparently, the coupon actually requires you to purchase something along with the free tacos but most of the employees couldn’t be bothered. God bless them.