Question: What episode of "How I Met Your Mother" had the American musician Keith Konrad Slettedahl and had the lowest recorded viewership for season one?
Sentence (from "Keith Slettedahl"): In 2006, he appeared in the episode "Best Prom Ever" on the sitcom "How I Met Your Mother", playing a gig with his band on a High School-Prom.
Relevant evidence: Yes