Towel Day is celebrated on the 25th of May every year to honor the memory and works of Douglas Adams, the author of The Hitchhiker’s Guide to the Galaxy. The most common way to celebrate is to carry your towel with you, which some fans do everyday. The official site has other suggestions, and a schedule of Towel Day events from all over the world. And remember: Don’t Panic! Image by Flickr user SiRGt.