That sentence isn't the longest valid English sentence, for example, this sentence is longer. In fact, as that Wikipedia article says, you can extend that sentence as well:

> Thomas Tymoczko has pointed out that there is nothing special about eight "buffalos"; any sentence consisting solely of the word "buffalo" repeated any number of times is grammatically correct.

Anyone who wants to go down that rabbit hole, see https://en.wikipedia.org/wiki/List_of_linguistic_example_sen...

I never herd that before, thanks.

Not everyone is made for herding buffalo.

I love that the article has a diagram with Buffalo from Rochester, NY too LOL

It's the longest grammatically correct sentence composed entirely of one repeating word.