We toss this flippant phrase around all the time—but it actually rubs a lot of people the wrong way. (Seriously, it's a thing!)

There's a (seemingly) harmless expression that, as it turns out, causes some people's hair to stand on end, especially in the workplace. The offender: "No problem."

I say it. You say it. We pretty much all say it—often on a daily basis and typically in place of now-synonymous responses like, "of course" when asked to do something, or "you're welcome" when someone tells us "thank-you." No harm meant, right? Apparently it's a bit more nuanced than that.

My first time hearing about this blacklisted phrase came from my first boss at my first job. She mentioned in passing that getting "no problem" or "no worries" in reply to any request irked her. Completely taken aback, I started to panic. I'd never heard this opinion before, and I didn't think there was a number high enough to count how many times I said "no problem" a day. I thought I was being pleasant, professional, and obliging! Now I worried that I had been rubbing important people the wrong way through various modes of communication without even knowing it.

Being an eager-to-please young professional, I listened to my manager like she was teaching me how to breathe. (I may have even written "stop saying 'no problem'" in my notebook.) But while I tried to burn it into my brain, I still didn't really get it.

What's so bad about saying "no problem" anyway? Her declaration seemed a little harsh at first, a little unforgiving—isn't saying "no problem" just a colloquialism for "sure" or "you're welcome"? Was her aversion to hearing the phrase a personal pet peeve, or is this a widely despised expression they didn't teach me about at the college career center? I hated to think some well-meaning person was going around unwittingly disrespecting others by saying "no problem" instead of "you're welcome." (And I hated even more to think that person was me.)

And then I started managing a direct report myself, and she hit me with a casual "no problem" on her first day. I wouldn't say I was annoyed at her, but something did click, and my first boss's firm stance on the matter started to make some more sense. I couldn't quite put my finger on why, but there was something in the way the response came across to me that made me cock my head and wish she'd been a little less off-the-cuff with me on her first day.

Was I actually incensed by her answer? Of course not, and she meant nothing by it other than to be her naturally cooperative, conscientious and hard working self. But I did finally come to understand why some people could take it the wrong way, and some of the more layered implications that this two-word phrase can have.

Maybe it's a generational thing, or perhaps it's simply contextual, but tons of people (not just my first boss!) can't stand to hear "no problem" because they associate the response with its literal meaning—and the implication that there is, was, or could actually be a problem. It makes perfect sense then for, say, someone's professional superior or even a customer talking to customer service to bristle at hearing "no problem." It could put them on the defensive, thinking: "I know it's no problem. I'm not asking you for a favor, this is your job!"

Now you might be self-conscious about using "no problem." If you think you've overused—or misused—this potentially troublesome expression to the point of irritating an important person in your life, simply swap it out for any number of easy, friendly responses (a few favorites: "you're welcome," "my pleasure," "any time," "absolutely," "yes"—you get the idea). But the truth is that a large portion of people have no problem (sorry) with hearing or using this slang phrase themselves.

As a matter of habit, I now avoid saying it like the plague, just in case (that first boss taught me well). But, for the record, I couldn't care less when people say it or write it to me. Seriously, it's no problem.