Shíshì shīshì Shī Shì, shì shī, shì shí shí shī.

The Lion-Eating Poet in the Stone Den or

« Shī Shì shí shī shǐ »

Shíshì shīshì Shī Shì, shì shī, shì shí shí shī.
Shì shíshí shì shì shì shī.
Shí shí, shì shí shī shì shì.
Shì shí, shì Shī Shì shì shì.
Shì shì shì shí shī, shì shǐ shì, shǐ shì shí shī shìshì.
Shì shí shì shí shī shī, shì shíshì.
Shíshì shī, Shì shǐ shì shì shíshì.
Shíshì shì, Shì shǐ shì shí shì shí shī.
Shí shí, shǐ shí shì shí shī, shí shí shí shī shī.
Shì shì shì shì.

Confused? From Wikipedia:

The Lion-Eating Poet in the Stone Den (Simplified Chinese: 施氏食狮史; Traditional Chinese: 施氏食獅史; Pinyin: Shī Shì shí shī shǐ) is a famous example of constrained writing by Zhao Yuanren which consists of 92 characters, all with the sound shi in different tones when read in Mandarin. The text, although written in Classical Chinese, can be easily comprehended by most educated readers. However, changes in pronunciation over 2,500 years resulted in a large degree of homophony in Classical Chinese; so the poem becomes completely incomprehensible when spoken out in Putonghua or when written romanized.