Later this month...

May 25th is Towel Day, a tribute to author Douglas Adams, who died in 2001. Fans carry towels throughout the day.

From the website’s FAQ:
"Should I really carry a towel all day? It might be embarrassing!

"Yes, you should really carry a towel with you all day. You might get teased or looked at weird, but then you can just hide behind your towel until the offensive people go away."