Nicknames in the Workplace: What is your Threshold?

A few weeks ago, I received a message from a former colleague on LinkedIn. We were catching up with each other's respective job or title changes, when he did something I still can't shake. 

He called me 'kiddo.' 

While I'm certain he meant no harm in the term of endearment, it bothered me because his wasn't an isolated incident. I often get called 'kiddo' by other professionals and by other adults, many of whom tease me about how young I look compared to them. (I swear this isn't a humblebrag. It's more of a blessing/curse situation as I have a round face, dimples, and highly-SPF'd skin). 

Despite how youthful my appearance often is, I'm not a kid by any stretch of the imagination. I've been out of college for a couple of decades and during that time, I've amassed quite a bit of personal and professional maturity and experience.

Being called 'kiddo' feels demeaning and small, as if I'm not qualified to sit at the same table or be in the same room as other professionals (or adults as in my social life). I'd rather be called "M'am" every single day if it means shaking the 'Kiddo' moniker.

The nickname or term of endearment has really gotten me to thinking about how I, too, refer to colleagues and friends.  At the office, the growing trend seems to be to refer to people by their first initial or their last name "Hey, E, how's it going?" or "Um, Smith, what's the status of Project Y?" No one seems to have any issues with that, which is good, but I know other companies or people aren't so lucky when it comes to nicknames.  

Let me know what you think, either in the tool below or via comments. What is your threshold for nicknames at work? Are you okay with kiddo? Does anyone have any fun nicknames they want to share?