So this is for a very limited amount of people but oh well. If you have a T-Mobile account and you're a member of their perks program, log in and there's a survey on it that gives you a free $5 Subway gift card. If you're not in the perks program, not sure how you join, I got an email about it and I only signed up a couple months ago.
http://my.t-mobile.com
http://my.t-mobile.com