Janet's Little Helper is the eighteenth episode of Season 7 of Three's Company, and the 146th overall episode in the series. Written by David Mirkin and directed by Dave Powers, it first aired 15 March 1983 on ABC.
Summary[]
As a surprise for Jack and Terri, Janet bought a used stereo which she asks Mr. Furley to fix. Unfortunately, Furley knows nothing about electronics but his shy teenaged nephew Marc does. In exchange for the repairs, Janet promises to help Marc overcome his shyness with women. Marc, who's embarrassed, asks Janet to keep their talk a secret. When Jack sees Janet out with Marc and Janet lies about it when confronted, Jack and Terri think Janet is going to have an affair with the adolescent.
Terri decides the only way to prevent this from happening is to get Marc a girl his own age. She recruits Julie Lipton, a candy striper from the hospital. Julie mistakes Jack for her blind date and throws herself on him when Janet enters the room. Janet, thinking Jack is dating a girl half his age, is shocked! Jack then confronts Janet about Marc. After Janet explains, Jack sheepishly realizes his mistake.