https://admissions.csbsju.edu/register/tshirt -for kids in Grades 9-12. Coupon code is not required.

https://prospects.uchicago.edu/register/?id= -high school seniors can request a free t-shirt from The University of Chicago

https://www.hi-chew.com/rewards/store#/ -register, then participate in the challenges to earn enough points.
The Konami code is: Up-Up-Down-Down-Left-Right-Left-Right B, A -enter this on your keyboard using the arrow keys and the letters b and a.
For the Fruit combo, go to the homepage and click green apple, mango, cherry in that order and you’ll get the points. –Update– they’re out of stock, hopefully they’ll restock items soon. I’ll update if they come back.

Link – get 5 friends to sign up for their contest to get a Pulstar Hat, 10 friends to get a Pulstar Fender Gripper, 25 to get a Set of Pulstar Plugs (up to 10), and 50+ friends to get a Pulstar Pit Crew Shirt

http://www.thefire.org/student-network/register/ -school name required

http://www.asbestos.com/wristbands/ -copy paste the link

http://shotcost.com/deal/sale/1245/ -for new customers only

https://www.fanfueled.com/WeAreBig -sign up and complete some tasks and you can spend your points on a free t-shirt

https://secure2.sophos.com/en-us/lp/sysmas.aspx?&orig=forums.free-stuff -job title and company name required. You have to sign up for a Sophos Cloud trial