Terry Pratchett has a sense of humor. He’s been spotted wearing this amusing shirt at least at one convention, and it explains why he’s there. Most conventions would list J.R.R. Tolkien as their first choice (duh) but given the fact that he’s uh, not available, the list eventually comes down to Pratchett. Of course, he’s selling himself short. He’s a talented author and the Discworld series and Good Omens are well-known and beloved – fans are thrilled to have him at any convention.