Grammatical pet peeves

[Phosphene]

What are your grammatical pet peeves? Here are some of mine:

It bothers me so much when time is at the end of a sentence when it is written like 8:30 A.M. There's a period at the end of the sentence, but because it's written like that it bothers me. So I have to write it 8:30 AM.
When people say your instead or you're. A really common thing but it still bugs me for some reason.
I know there are more, but I wouldn't remember unless I saw them.

What are yours?

[Moriya]

My main annoyance is when people make run on sentences. Just use a period. If you want people to think you're a genius; then, use a semicolon.

[everlong]

A lot of language Tumblr users use annoys the crap out of me. Like when they start their sentences with "okay but" or when they're seNTENCES BECOME CAPITALIZED OUT OF NOWHERE COMPLETELY UNNECESSARILY.

[heresjohnny]

My main annoyance is when people make run on sentences. Just use a period. If you want people to think you're a genius; then, use a semicolon.

Absolutely.

Separate thoughts shouldn't be split with a comma, it just looks bad.
It's nearly half-past five, we can't reach town before dark.
https://en.wikipedia.org/wiki/Comma_splice