Towel Day is May 25th, an annual celebration honouring Douglas Adams, author of The Hitchhiker's Guide to the Galaxy.
Origin
Douglas Adams died on May 11, 2001. Two weeks later, fans organised the first Towel Day as tribute. The date has been observed annually since.
Why Towels?
In The Hitchhiker's Guide, Adams declared towels "the most massively useful thing an interstellar hitchhiker can have." The passage elevates the humble towel to cosmic importance.
How to Observe
Carry a towel all day. That's it. Visible towel-carrying shows solidarity with fellow fans.
"Know Where Your Towel Is"
The phrase became cultural shorthand for being prepared and competent. Adams wrote that anyone who "still knows where his towel is, is clearly a man to be reckoned with."
Global Participation
Towel Day is observed worldwide, with particular enthusiasm in geek and science fiction communities. Social media lights up with towel photos each May 25th.