You enter a bookstore. At first sight, everything seems normal. Your first red flag occurs when you pick a book up. Perhaps the colour on the cover is a little off. Perhaps some pages are printed askrew. Perhaps the pages are flimsier, and you can make out the words printed on the other side of each page. 

Or perhaps the contrast of the ink is slightly off, and you have just spent the last hour staring at Figure 6.2 and still can't make out what that arrow is pointing to.

You look around the dimly lit room. You notice the signs duct-taped over each dusty bookshelf, and it hits you. In lieu of the normal classifications "fiction", "Non-fiction" ... etc, the signs simply read RMB/斤 (price/weight).  

Yes, books are sold by their weight. You compare books and find that Revenge Wears Prada costs more than Stephen Hawking's A Brief History of Time, simply on the basis that it contains more pages. 

Dayum. 

You bring your books to the counter, and true enough, the store assistant dumps the books onto a scale. You hand over your money, he grunts and then you're off. 
You exit the store and squint in the strong sunlight. People rush around you, caught up in their own activities. Some scan the two rows of stores alongside the road and pass the bookstore where the storekeeper sits, calmly weighing books and conducting his daily business, as if nothing at all was unusual. And you can't help smiling a little at the chutzpah of it all.