There are quite a number of various Golly Badges. The Golly
Badge official website has links to pictures of twelve separate
examples of Golly Badges.
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By Golly - 1920 was released on:
USA: 6 June 1920
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It means "you bet." The "by golly, wow" is just added for
emphasis.
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The word golly is used to express the emotion of surprise or
delight at something. When having some good fortune one might say
'golly what a stroke of luck that was'.