In this episode Betty and Wilma are fawning over some Hollywood phony resembling Cary Grant. They see him doing all these ridiculous things on TV and assume that it's real. And like a lot of women do they compare their husbands to that and laugh. Fred of course can see right through it and realizes that the guy is the phony and doesn't do all those stunts.
So when there is a contest to win a role on the show that this phony is in Wilma writes a letter using a phony name for her husband and telling the studio that he is a world champion athlete and that he wrestles dinosaurs and so forth. When they get to Hawaii Fred finds out that he only has one line but then when they read Wilma's letter again they decide to make him a stunt man doing all these dangerous things while the phony just sits back and does nothing showing Wilma and Betty that he really is a phony and does none of the things that they see on TV.
So in my opinion this was Wilma and Betty at their worst - using their husbands to get a free trip and fawn over a phony.