Byron Han shared this article  by Jian Shuo Wang about a Chinese poem written in 1930 in which every word is "shi" .
Here's the text of the poem:
I selected this text and told my Mac to "Start Speaking". For some reason in my System Preferences I had the "Kyoko" voice selected at the slowest speed, so it came out sounding like a drunk Japanese woman.
I changed to the "Ting-Ting" voice at normal speed and heard it in mainland Chinese as intended. Fun!
In Cantonese (the "Sin-Ji" voice) the words are not only different from Mandarin but much more different from each other than in Mandarin. In Cantonese most of the syllables are "see", a few are "sik", quite a few are different altogether. This did not surprise me.
What did surprise me was how it came out in the Taiwanese voice ("Ya-Ling"). I had thought mainland and Taiwanese Mandarin were pronounced the same word for word, with the only difference being a matter of accent, the way Minnesotans pronounce harder R's than Californians. But it turns out there are some words that are pronounced completely differently.
Wang gives a translation of the poem in his blog post. Rather than copy it here, I suggest you visit his blog at the link I gave. I like what Google Translate returns, especially the phrase "relies on the vector potential":
The sarcophagus poetry Guests Amur, addicted to food lion, oath eat ten lions. Suitable Amur always suitable for the city, as the lion.Ten o'clock, fitness, fitness ten lions. Yes, the appropriate Amur appropriate city. 's Depending on those ten lions, relies on the vector potential, so that the death of ten lions. S pick the ten lions corpse, fitness sarcophagus. Shishi wet, that's so paternity swab sarcophagus. The sarcophagus the swab,'s start tasting is ten lions corpse. Food before consensus is ten lions corpse, the real ten lions corpse. Interpreting things.
I used the Mac's "
say -o" command to generate the above audio files. The output was in AIFF format, which I converted to MP3 using an app called "Music Converter".
UPDATE 1: Edited to mention Jian Shuo Wang by name, and to mention that he offers his own translation of the poem.
UPDATE 2: It occurred to me that a person claiming to be a native Mandarin speaker could be tested by being made to read this poem aloud. In theory a real native speaker would have less trouble getting the tones right than a faker, making this poem — dare I say — a sort of "shi-bboleth".
 Actually Byron linked to an article on Shanghaiist.com, but I'm linking here to the original article which it links to.
 Note that "shi" is not pronounced "shee" as you might think. It's more like the English word "shirr". It amuses me that the word "是" by itself, which means "Yes" or "Okay," sounds like "Sure." It's an affirmative answer in two languages.