Lost in translation

When I was little, I had a yellow pencil case from Japan on which was written the following legend: "Duck on up and come on down."

What did it mean? I have no idea, but I loved that pencil case with all my 6-year old heart.

Clearly the designer of the pencil case had no idea either, but he or she just liked the look of the English words. They added a certain something something to an otherwise prosaic pencil case.

Similarly, behold this 1951 dress from the House of Dior, adorned with Chinese characters, which Christian Dior couldn’t read, obviously, or he would have known that they were from an eighth-century letter in which the author, Zhang Xu, complains about a painful stomachache.

Here's a full translation of the text, courtesy of the University of Pennsylvania's Language Log: 

Suddenly [I feel] an unbearable pain in [my] abdomen

[I] don't know whether it is caused by cold or by heat

If I take a rhubarb preparation, it should be efficacious whether my condition is cold-related or heat-related

 [But] how to make the decoction, since I'm not near a market?