Don Knuth at Stanford University collects signs.
Actually he collects photos of signs, especially the diamond-shaped informational-warning signs.
What in the world is this one?
A sign photographed in Australia, in the Knuth Collection.
Your nominations for captions welcomed in comments.
More, sorta — or maybe, “tangentially related” is a better description:
Donald Knuth at a reception for the Open Content Alliance, hosted by the Internet Archive. Taken October 25, 2005 by Jacob Appelbaum in San Francisco. (Wikipedia image)
- Don Knuth and the Art of Computer Programming: The Interview (adafruit.com)
- Can (and should) scientists become great presenters? (presentationzen.com)
- You might enjoy some of the other posts on signs here at Millard Fillmore’s Bathtub
Posted by Ed Darrell 
Millard Fillmore's Bathtub 