The Cosby Show: Season 6, Episode 17
Not Everybody Loves the Blues (1 Feb. 1990)
Theo is upset his girlfriend might go to graduate school in another town. He and Elvin go to a nightclub; they hear the King of the Blues Riley Jackson. Turns out Cliff & Claire know Riley. He visits the family, helps Theo with his blues.
From $1.99 on Amazon Instant Video