I know I said that this grammar post would be about punctuation, but this just couldn’t wait.

This ad came up on my Words With Friends game and I almost gagged. Can you spot the grammatical mistake? (The title of this post probably gave it away.) If you didn’t catch it right away, you’re not alone. This is one of the mistakes I spot most frequently and is quickly becoming my biggest pet peeve. I see it on signs, on ads, on letters, on every social media site imaginable, and it must be corrected before my head explodes.

So here you go. We are going to clear this up, once and for all. Are you ready?

Every day is an adverb, meaning each day. Everyday is an adjective, meaning ordinary and commonplace.

Here’s a tip I got from The Essay Expert: Add the word “single” between “every” and “day.” If it makes sense, the correct word is every day. If it sounds completely ridiculous, it’s everyday.

See the difference? You’ll never confuse everyday and every day again!

(But really, you better memorize this. Sooner or later, I’m going to start throwing water balloons at people that misuse “everyday.” And I’m going to do this every single day.)