I swear  someone asked me this exact question at the library yesterday :

When I first read this (now defunct) Unshelved comic strip several years ago, I dreamt to answer exactly like Dewey did if I ever found myself in this situation. Unfortunately, such sarcasm would be considered very poor customer service so I abstained. After a long pause, I smiled (actually, I barely resisted laughing out loud) and I referred  the customer to the reference librarian. Always do like the t-shirt says: “Keep calm and let the librarian handle it” !

It reminds me of this situation, years ago, when I was trying to make a library card for a guy who didn’t want to give his personal information because he was an anarchist and he didn’t want the big-brotherly government to know anything about him. Incredulous, I said to the guy: “Wait a minute. You say you are an anarchist, but you want to benefit from all the free library services? Don’t you think it’s a little hypocritical?” He seemed unfazed but, since he refused to provide any of the required information, I couldn’t register him to the library. I found such audacity unbelievable. We really see the strangest stuff in a library…