25th May is celebrated as Towel day every year as tribute to an English Author Douglas Noel Adams (11 March 1952 – 11 May 2001). This commemoration started two weeks after his death, on 25th May 2001.
In this day, fans of Douglas Adams carry a towel publicly with them. This is in remembrance of the author and his famous book The Hitchhiker's Guide to the Galaxy, also known as H2G2. In this book, author demonstrated the importance and usefulness of a towel with world famous phrases and caption.