A Massachusetts library's message to customers who come in and ask for a book by the colour of its cover has gone viral.
The Framingham Library put together a display featuring several red books and a simple sign on top.
"I don't remember the title, but the cover was red," the sign said.
A library patron took a photo of the display and posted it to Twitter, but he wasn't quite prepared for the response it would get.
The image was retweeted over 43,000 times and received more than 116,000 likes.
But what was shocking was how many people responded to say they received that question a lot, or had their own similar display.
"I love that so many responses to this are people asking their friends who work in libraries/bookstores 'did this ever happen to you?' (The answer is always yes.)," user Metafrantic said.
One user responded by sharing what was called a library secret of how to guess what book somebody was after.
"Customer: 'It's this big,' *indicates with hand gestures* 'and it's red.'," the user wrote.
"Me (Bookseller): 'It's 'The Dangerous Book for Boys'.
"Customer (unaware that I'd sold 15 copies that morning as it was the book du jour): 'YOU'RE A WIZARD!'
"Me: 'A BOOK WIZARD!'"