Illustration of the Scream character surprised by grammatical errorsWhile most people are screaming at haunted houses this Halloween, at WriterGirl, something else makes us shriek. More than clowns in sewers, ghosts in attics or monsters under the bed, what scares us the most is improper grammar. Let’s talk about the top five grammatical errors that make us scream “AHHHHH” this Halloween and all year round.

1. The importance of commas.

A comma can make all the difference between writing an innocent statement or looking like a murderous cannibal. For example:

Let’s eat Grandma! (What? No!)


Let’s eat, Grandma! (Oh – OK!)


I like cooking my family and my pets. (What? Ew!)


I like cooking, my family and my pets. (Oh Me too!)

(Note: The lack of the Oxford comma before the “and” is a conversation for another day!)

2. They’re vs. their vs. there.

They’re, their and there are three different words. Let’s learn the difference, Halloween style:

The vampires are over there.

Their stomachs are empty.

They’re going to suck our blood.

Got it? Now run!

3. Your vs. you’re

Your and you’re mean two different things — especially if a friendly witch sends you a dinner invitation:

You’re dinner is here! (Um – what?)


Your dinner is here! (Oh – Yum!)

4. Apostrophes

Apostrophes can be confusing, but should only be used in these instances:

  • When writing a contraction. (Example: I can’t go to the Halloween party.)
  • When showing possession. (Example: The mummy’s bandage got stuck in the slime.)

Also, note that apostrophes should never be used with plurals (unless to show possession, of course!)

  • Incorrect: The witch’s lost their hats.
  • Correct: The witches lost their hats.
  • Incorrect: The witches hats were lost.
  • Correct: The witches’ hats were lost.

5. Affect vs. effect

An easy way to remember the difference between affect and effect is that:

  • A = action (affect, which is also a verb)
  • E = end result (effect, which is also a noun)

For example:

  • The ghosts affected our visit to the cemetery.
  • The sunlight has a bad effect on the vampire.

Read a similar post: I use ineffective healthcare writing techniques, and you can, too

Quiz time!

Now that we’ve discussed the top five grammatical errors, let’s see what you’ve learned. Can you spot the errors in the Halloween invitation below?

Your invited!

Where: The Witch’s House

When: October 31st

What: Lets party! You’re dinner!

The Witch’s have a fun-filled evening planned for people of all ages. We’ll have several activities available, such as:

  • Learning to cut and paste kids
  • Carving pumpkins
  • Monster mashing

Theirs something for everyone at this party! Missing out will effect your life — or what’s left of it! Moohahahahahaha.

Time for a laugh

And finally, let’s end with a Halloween joke because, after all this screaming, it’s nice to have a laugh:

What’s the difference between a black cat and a comma?

The black cat has its claws at the end of its paws.

The comma is a pause at the end of a clause.

Happy Halloween!

Who you gonna call?

Ready to spook away grammatical errors from your organization? Contact WriterGirl to learn how we can help!

Editor’s note: This post was originally published in October 2018. It was updated on October 5, 2022.