"Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo." is a grammatically correct sentence.

The story behind the answer

True. It’s grammatical because “Buffalo” (capitalized) is the city, “buffalo” (lowercase) is the animal (bison), and “buffalo” is a verb meaning “to bully.” Parsed, it means: Bison from Buffalo that bison from Buffalo bully, themselves bully bison from Buffalo. It uses noun modifiers (“Buffalo buffalo” = bison from Buffalo) and a reduced relative clause (“[that] Buffalo buffalo buffalo”).

Linguists highlight this sentence to illustrate homonyms, ambiguity, and recursion; it was popularized by William J. Rapaport at the University at Buffalo. Memory tip: think Place–Animal–Action, repeated—city bison (who are bullied) bully city bison.