I always thought the best quote was "Just a slight stiffness," but now that you've mentioned it, I think the "other guy" quote may have had something to do with Lazenby's brief tenure.
I have thought and thought about it, and decided that Lazenbys best line occurs when he visit M at his estate.
M is mounting butterflies as Bond is ushered in and Bond states something like “unusualy small for a Pollycloris Bergenatis, and M says something like “I didn’t realize your knowledge extended to Lepidoptery” or some such.
That was awesome.