To enter simply retweet the following message up to 1x per day until the end of the contest:
Win a free tee from @Gryphony and @FashionablyGeek. Follow @Gryphony and RT. 2 winners chosen randomly. http://bit.ly/dGHt0R #giveaway
Two winners will be chosen randomly after all entries have been processed. The contest is open to US residents only. Good luck!