Sentences employing the same word over and over are one of the more head-scratching oddities. These are grammatically correct sentences that use just one word repeatedly. Once example is:
Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo
The repetition takes advantage of a mix of three distinct meanings while combining verbs and nouns that are all spelled buffalo. The uppercase Buffalo refers to a proper noun, such as the New York city of Buffalo. The lower case buffalo has two distinct meanings. Buffalo is a noun that refers to a large wild ox with large horns (such as the water buffalo). A buffalo is also known as a bison in North America. Buffalo is also a verb, meaning to intimidate or baffle.