you got that wrong.
James, while John had had “had”, had had had “had;” “had had” had had a better effect on the teacher.
the “while” should probably be changed to “whereas,” too.
“while John had had had”
is a subordinate clause. the primary idea being conveyed in that sentence is that john had had “had.” next, your sentence would be a run on without the semicolon (or perhaps an emdash would also be acceptable). You also failed to denote which instances of the word “had” were references to the use of the word and which were verbs.
on to the buffalo sentence.
Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo.
you got that wrong too.
“Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo.”
is the correct sentence–minus a bit of punctuation. once again there is a subordinate clause which must be indicated by commas.
Buffalo buffalo, Buffalo buffalo buffalo, buffalo Buffalo buffalo.
Buffalo (as in the city) buffalo (as in the animal), Buffalo (city) buffalo (animal) buffalo (bully), buffalo (bully) Buffalo (city) buffalo (animal).
in other words:
Those Buffalo buffalo, who, ironically enough, are themselves buffaloed by Buffalo buffalo, buffalo Buffalo buffalo.
now ordinarily i wouldnt nitpick as much, but i know that you got those sentences from wikipedia where the grammar is explained in great detail and you therefore should have known better.