Believe it or not, that is a grammatically correct sentence in American English!
How is that possible?
Well, consider the fact that “Buffalo” is a city in New York, while “buffalo” means to bully or intimidate, as well as being a synonym for bison.
So: Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo
New York bison whom other New York bison bully, themselves bully New York bison.
Phew, even the explanation sounds like a tongue-twister! On the subject of tongue-twisters, here are some of my favorites:
As I was in Arkansas I saw a saw that could out saw any saw I ever saw saw. If you happen to be in Arkansas and see a saw that can out saw the saw I saw saw I’d like to see the saw you saw saw.
She stood on the balcony, inexplicably mimicking him hiccupping, and amicably welcoming him in.
A pessimistic pest exists amidst us.
The sixth sick sheik’s sixth sheep’s sick.
Yours in crisp, error-free writing,