And Something Makes Three - S1-E12
Other mistake: While Gladys Kravitz is standing in front of her house, which is across the street from the front of the Stephens' house, Gladys sees the Stephens' backyard just as Sam zaps a swimming pool and then zaps it away, but since the Stevens' backyard is located behind the house where the living room and dining room are, this would be impossible even for nosy Gladys Kravitz.
Answer: Telstar was an early communications satellite system. Darrin, in a particularly sexist manner reflective of this era, is saying that telling a secret to a woman means it is guaranteed to be "broadcasted" to multiple people.
raywest ★