Weird but grammatically correct!
The word “buffalo” has three different meanings. It’s the name of an American city; it’s a name of an animal also known as bison; and it’s a verb, meaning “to bully, harass, or intimidate”.
So “Buffalo buffalo buffalo Buffalo buffalo” would mean something along the lines of “The buffalo from Buffalo buffaloes (bullies) the buffalo from Buffalo” – two bison from Buffalo are in a turf war, and one is harassing the other.
Syncronistcally I read this immediately after using the word in Keep one Drop One.