Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo

that's a grammatically correct sentence. here's why:

The sentence is unpunctuated and uses three different readings of the word "buffalo". In order of their first use, these are

• c. The city of Buffalo, New York (or any other place named "Buffalo"), which is used as an adjective in the sentence and is followed by the animal;
• a. The animal buffalo, in the plural (equivalent to "buffaloes"), in order to avoid articles and is used as a noun;
• v. The verb "buffalo" meaning to bully, confuse, deceive, or intimidate.

Marking each "buffalo" with its use as shown above gives

Buffalo^c buffalo^a Buffalo^c buffalo^a buffalo^v buffalo^v Buffalo^c buffalo^a.

Thanks Wikipedia!