Lyric discussion by engravement 

I always though Malkmus was the "S" dog. This writer agreed:

magnetmagazine.com/2001/04/01/stephen-malkmus-being-stephen-malkmus/

(This is the part of the story that’s in parentheses. It’s just a theory, and Malkmus, notoriously reluctant to reveal himself in his songs, would never admit this, but I think the song “Jenny & The Ess-Dog” from his solo album is really about their relationship. Some of the names have been changed, but you don’t need a secret decoder ring to figure out who the “S” Dog is. Even though the facts have been disarranged—“She’s a rich girl, he’s the son of a Coca-Cola middleman”—the song has the same vibe Malkmus and Larimer give off when they’re together. It sounds like summer, like falling in love. It’s the catchiest song he’s written since “Cut Your Hair.”)

back to my thoughts: SM is the son of an insurance salesman. He says he never writes anything literal, but that's not far off.

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