One can't buffalo buffalo without thinking of the two old standbys:

The horse raced past the barn fell. (http://en.wikipedia.org/wiki/Garden_path_sentence)

John while James had had had had had had had had had more fun. (That one was from an old puzzle book I had—had had?—as a kid. I find it much like the Buffalo sentence, in that you puzzle over it for a while, are told the resolution, and then say “Huh. OK, if you say so.”)

EDIT: While my mind's on random funny sentences, this one was an old favourite of my mother's (who taught me all the grammar I know) from Cheaper by the Dozen. It is the reaction of a child, whose bedroom is on the second floor, on being presented with an unacceptable evening's reading: “What did you bring that book you know I don't like to be read to out of up for?”