Answer by Nishit Jain:
Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo.
No, really. There's a whole Wikipedia page on it –
The sentence's intended meaning becomes clearer when it's understood that it uses the city of Buffalo, New York and the somewhat-uncommon verb "to buffalo" (meaning "to bully or intimidate"), and when the punctuation and grammar is expanded so that the sentence reads as follows: "Buffalo buffalo that Buffalo buffalo buffalo, buffalo Buffalo buffalo." The meaning becomes even clearer when synonyms are used: "Buffalo-origin bison that other Buffalo bison intimidate, themselves bully Buffalo bison."