Wikipedia entry on an odd but grammatically correct sentence:

Buffalo buffalo, Buffalo buffalo buffalo, buffalo Buffalo buffalo.

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" or "buffalos"), in order to avoid articles (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).

Thus, the sentence when parsed reads as a description of the pecking order in the social hierarchy of buffaloes living in Buffalo:

[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 ALSO buffalo THE buffalo FROM Buffalo.