The fact that five of the “hads” are not semantically the word “had” but rather a quotation makes this one weaker than “Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo” imo, though you could argue that Buffalo as a proper noun is also kinda cheating.
The fact that five of the “hads” are not semantically the word “had” but rather a quotation makes this one weaker than “Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo” imo, though you could argue that Buffalo as a proper noun is also kinda cheating.