It occurs to me that you can have a lot of fun, not only with the "buffalo" sentence, but also with other similar forms. For example, "Mississippi misses miss misses Mississippi misses miss", which is sort of self evident. Also, "Robbers rob robbers robbers robbers rob rob". Longer sequences can be formed in the same way that long "buffalo" sentences are formed, by forming categories and then having one category miss, or rob, another category.
Have fun. Can you find other nouns and verbs that make long fun sentences?