My partner passes as a straight cis white dude and works in finance and you are right, within the first interaction of meeting a bigot they will open their mouths and out themselves. And the worst part is, they nearly always phrase it as an in-joke, or an in-thing, like they are figuratively 'wink wink nudge nudging' him and it drives him fucking crazy that they just assume he's one of them and will nod or laugh along. Instead, he pulls a reverse uno and shames them, very politely, for various super neutral reasons: like not being professional and staying on topic, or for being a hr violation, etc. He's found the less progressive, more business-neutral language really fucks them up, they get super embarrassed