Yes, I Admit It. I Belong to the Grammar Police.

I just saw a cartoon on the Grammarly page on Facebook that I have to share here, seeing as I am a card-carrying member of the dreaded <cue creepy music>, dare I say it, Grammar Police.
From the Grammarly page on Facebook
Yes, I admit it fully. Sometimes I wish I weren't — that I could blithely skip my way through articles, emails, posts, tweets and texts — my eye not catching and stopping as dead-on an error as if it were a flashing red neon sign. But I can't. I think it's genetic. My mother has it. My children both have it. Luckily, I'm in very good company — many of my friends and colleagues are also members.

I know we bug the heck out of the grammar unconscious, but we can't help it. Really. (This week's itch, caught in Huffington Post at least twice: There is a difference between rein (control) and reign (royalty). Look it up if you're not sure.)

If you aren't a member of the Grammar Police, I'll let you in on a secret. Errors in our own writing hurt us more than the errors in your writing do. So there's probably some cosmic justice (or joke) taking place. Because you don't care about our grammatical errors and typos if you don't belong to the Grammar Police, and probably don't even notice them. We however, blush painfully and immediately look for the edit button when we re-read our stuff and catch any error.

A question for my Grammar Police brethren: What grammatical errors do you find most grievous? Share please! :-)