Batman doesn't wear his underwear on the outside of his pants. His costume is based on the standard 30's acrobat unitard, which had a reinforced brief. It was exterior both for comfort (since the lighter fabric of the unitard proper was inner) and for modesty (since Unitards... er... outlined things). If you look at acrobats, weightlifters, or anyone else wearing a costume or uniform designed to highlight their body at the time, they generally had a similar brief as part of the costume.

...pedantic? Me?

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I had a response but then I've deleted it since it needs to be an actual strip.

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Then my work here is done. :)

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And it's a very good strip.

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