The Lucy Show - Season 5 - Episode 14 - Lucy's Substitute Secretary

Lucy is preparing to go on vacation, but she has a change of heart when her substitute secretary turns out to be an attractive blonde who Mr. Mooney really likes. Lucy secretly doesn't go on vacation, and spies on them in various disguises.

Creators: Bob Carroll Jr., Madelyn Davis, Bob Schiller
Starring: Lucille Ball, Gale Gordon, Vivian Vance, Jimmy Garrett, Sid Gould, Ralph Hart