Looked at my receipt from Starbucks. Advertised down the bottom is a wrbsite link with a unique code, fill out a short survey an you get a free tall beverage (tall? Technically the smallest option in their sizes)
Your required to put your customer survey number on the receipt and give it with your selection. There is no system to check. Write any number as long as it starts with 03.
This is not posted as a deal as I'm unsure how wide spread this promo is. Feel free to let me know of anyone else can confirm with location.
Thanks Moots, I'll look into it tomorrow.