What is good for the gander is good for the goose is an American idiom that is basically said to mean that if something that one individual is deemed acceptable then it should also be acceptable for another person.
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''What's Good for the Goose is Good for the Gander'' is a saying that means that whatever is good for a man or males is also good for a woman or for females. Gander is male goose and thus whatever is good for it should be good for all other geese. The saying is used to discourage sex discrimination.