All based around Stephen King and his opus The Dark Tower and his love of baseball and the Red Sox.
This shirt combines these elements... visually based on the Red Sox logo, replacing Boston with Gilead, the place in the Dark Tower series where Roland hails from. Roland is a gunslinger, hence the team name I've applied plus replacing socks with guns. The number 19 and the rose are common references throughout the series (seen here on the gun stocks) plus the title of the shirt has 19 letters, tying it back in.
This is one for all the fans out there.