Avoid this holiday card grammar mistake. Here's how to make your last name plural.

Nothing quells my Christmas cheer as quickly as a stray apostrophe. Every year they assault me.

Usually, it’s in the middle of an otherwise quaint moment: I am padding around my parents’ house, wearing pink slippers, sipping on some hot chocolate. Snow is falling outside the window, and Josh Groban’s Christmas CD is filling the downstairs with peace on earth and mercy mild. My mother is baking a pie. She’s about to ask whether I want to lick the spatula (which, duh, I will).

First, though, I find a stack of Christmas cards and begin to flip through them, pausing to marvel at how big so-and-so’s kids have gotten. And then I spot it: an apostrophe in a last name that isn’t supposed to be possessive.

I shudder, flipping past the unwarranted punctuation. But as I keep flipping, the apostrophes do, too — flipping me off, that is. They defile Christmas card after Christmas card, last name after last name with their presence. Gone is my Christmas cheer! All my glad tidings, replaced with fury.

“Did no one teach these people how to make their last names plural!?” I scream as I chuck the cards into the fire heretofore crackling peacefully beneath the mantel.

I watch the cards curl and disintegrate in the flames, and I wonder if I’ve overreacted.

Is pluralizing last names more difficult than I realize? Apparently so. Because we get these cards every year, these cards with their adorable photos and their apostrophe catastrophes.

This year I’d like to pre-empt the pluralization problems. I have created a brief guide to help you pluralize your last name. It is my humble attempt to preserve not only apostrophe protocol but also the dignity of the letter “s.”

The definitive guide to pluralizing your last name

Pluralization FAQs and rules for names ending in 's'

Q: What if my last name ends in a “y”?

A: Add an “s.” Do not add “ies” or an apostrophe.

Merry Christmas from the Murphys.

Q: What if my last name already ends in an “s”?
A: Add “es.” Do not add an apostrophe.
Season’s greetings from the Simmonses.

Q: What if my last name is or contains an irregular noun?
A: It is not irregular when it is part of a last name.
Happy holidays from the Hoffmans. Warm wishes from the Wolfs.

Q: What would adding an apostrophe do?
A: It would hurt Tiny Tim. Or it would make your last name possessive.

Q: Is there ever a reason to add an apostrophe?
A: Only if you want to make your last name possessive.

Q: Why do people add apostrophes?
A: I have no idea.

If your goal is to make your last name possessive, then, by all means, use an apostrophe. If your goal is simply pluralization, however, forgo the apostrophe. In the spirit of the season, I beg you.

(Editor's note: This article originally appeared on KateBrannen.com and ran on ABC News in 2014. It has been reprinted here with permission. Brannen is “a rising grown-up, a recovering perfectionist and a recent grad of Asbury University and the Missouri School of Journalism.")