Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo

"Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo" is a perfectly grammatically correct sentence.  It is used as an example of how homonyms and homophones can be used to create complicated linguistic constructs. 

Cool, huh. XD

From Wiki:

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

• a. the city of Buffalo, New York, United States, which is used as a noun adjunct in the sentence and is followed by the animal;
• n. the noun buffalo, an animal, in the plural (equivalent to "buffaloes" or "buffalos"), in order to avoid articles;
• v. the verb "buffalo" meaning to bully, confuse, deceive, or intimidate.

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

Buffalo^a buffaloⁿ Buffalo^a buffaloⁿ buffalo^v buffalo^v Buffalo^a buffaloⁿ.

Thus, the sentence when parsed reads as a claim that bison who are intimidated or bullied by bison are themselves intimidating or bullying to bison (at least in the city of Buffalo – implicitly, Buffalo, NY):

• [Those] (Buffalo buffalo) [whom] (Buffalo buffalo) buffalo, buffalo (Buffalo buffalo).
• [Those] buffalo(es) from Buffalo [that are intimidated by] buffalo(es) from Buffalo intimidate buffalo(es) from Buffalo.
• Bison from Buffalo, New York, who are intimidated by other bison in their community, also happen to intimidate other bison in their community.
• THE buffalo FROM Buffalo WHO ARE buffaloED BY buffalo FROM Buffalo, buffalo (verb) OTHER buffalo FROM Buffalo.
• Buffalo buffalo (main clause subject) [which the] Buffalo buffalo (subordinate clause subject) buffalo (subordinate clause verb) buffalo (main clause verb) Buffalo buffalo (main clause direct object).

The sentence can be clarified by substituting the synonym "bison" for the animal "buffalo", "bully" for the verb "buffalo", and "New York" to refer to the state of the city Buffalo:

"New York bison New York bison bully bully New York bison", or:

"New York bison whom other New York bison bully, themselves bully New York bison".

But might be easier to read by leaving the city name intact:

"Buffalo bison Buffalo bison bully bully Buffalo bison".

Removing the classifier noun "Buffalo" (the city) further clarifies the sentence (note that the initial capital is retained as the common noun "buffalo" now starts the sentence):

"Buffalo buffalo buffalo buffalo buffalo."

"Bison [that other] bison bully [also] bully bison."