In 2006, Keith Slettedahl appeared in an episode of "How I Met Your Mother" that originally aired on which date ?
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. Best Prom Ever:  It originally aired in the United States on May 1, 2006.
May 1, 2006