https://www.treestuff.com/faq.asp?faq_id=16
How can I get some FREE stuff?
Easy. Go to one of our product pages and write a product review (good or bad) of an item you own or have used before, along with #shirt. We’ll send you a free TreeStuff shirt. Remember to include "#Shirt", your US mailing address, and your shirt size in the text of the review. This is how we find your review and send out your shirt, so you must include #Shirt to receive a free shirt.