If a Martian Answers, Hang Up (S01E18)

Herman's preoccupation with his ham radio set leads to difficulties when he mistakes some children at play for a group of visitors from another planet. In a nearby playground, two young boys play with a walkie-talkie set and decide to pretend that they are men from Mars. At the same time Herman's radio signal picks up the message and believes he has made contact with outer space. (iTunes)