The way this dude speaks. He exhales incredible intelligence!!!
In the interviews you can see that he pronounces names in all languages amazingly, making acute effort to do so, to the point of being notable. His passion for linguistics is actually mentioned on Genius: Richard Feynman and Modern Physics by James Gleick (1994).
Maybe this obsession is partly due to his name which no English speaking person knows how to pronounce from the writing.
This passion also led in part for his names to some physics terminology he worked on winning out over alternatives by his collaborators, most notably in the case of the naming of the quark.