I wonder what it means by "someone is in his/her underwear" both literally and figuratively? For example:
When people downvote your posts arbitrarily just imagine them in their underwear.
I wonder what it means by "someone is in his/her underwear" both literally and figuratively? For example:
When people downvote your posts arbitrarily just imagine them in their underwear.
I've only heard this expression in the context of being coached for public speaking, precisely as Sam I Am mentioned in his comment. (Quite frankly, I'm not so sure it's good advice, as I don't know how such mental imagery would help me concentrate on my speech - but that's another matter).
As for incorporating it into everyday speech, I'd (a) use it sparingly, and (b) say it as if everyone has already heard this somewhat tongue-in-cheek way of mentally equalizing people before. If overused, it could definitely turn into something that sounds rather juvenile.
As for your follow-on question (Can someone get in trouble for saying it?): Mentally undressing someone can be a form of sexual harassment. If you said, "Oh, just imagine them all in their underwear," in the workplace, and one person mistakenly felt you meant that literally, it's not beyond the realm of possibility that a complaint could be filed.
In this particular case, there's perhaps a thin line between using the idiom as a mere expression, and actually carrying out the words in a literal and leering way. So, if you're in a zero-tolerance environment, you might want to use a different idiom, just to be on the safe side. One such idiom I've heard is, "He puts his pants on one leg at a time." Ironically, that still revolves around people in a half-dressed state, but at least they're donning their clothes, instead of having them removed.
It is literal - you are meant to imagine people in their underwear. It's meant to be an equalizer of sorts, underneath our clothes we're all the same. Where I live, people more frequently say 'Imagine them naked', we're not so prudish.