Often times when screen printers are printing shirts, they test the printing screen with sort of a throwaway shirt, and this shirt is often re-used many times to make sure everything is working properly. Shirts of this type are extremely rare, as they are a 1 of 1. This particular tee looks to be a test print of a printer out of South Carolina, who did different sorts of tourist, college, and art tees.
Shirt is tagged Large on the Xpres Knits tee. In really good condition, but fits more like a medium.