I've been called 'straight' before, and I possess the superpower of being invisible to most gaydars.
I'm gender-neutral/gender-ambiguous in style and attitude. When I'm among machos, I'll appear effeminate, and when I'm among a more feminine crowd, I'll be 'the guy'. All my adult role models growing up were women, so I can imagine that that's contributed to how comfortable I've grown with my 'feminine sides'.
EDIT: I'm not hetero btw. Not that there's anything wrong with that 
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clarity of thought before rashness of action