The title of this entry (if you take “buffalo” to be 1) the obvious noun with identical plural, 2) capitalised, the proper noun referring to the American city, and 3) a verb meaning approximately “bully”) is a grammatically correct sentence of English. (I first came across it in The Language Instinct by Stephen Pinker, but was reminded of it recently.)
In fact, according to Wikipedia, for any n ≥ 1, buffalon is a grammatically correct sentence, if you disregard capitalisation. (“Buffalo!”, “Buffalo buffalo”, “Buffalo buffalo buffalo”, etc.)
Don’t you just love natural language?