It's been said that most people write how they speak.
This works for some things (like character dialogue). ...To a degree. (There are still dialogue choices you don't want to make simply because "that's how people talk." But that's neither here nor there.)
When we talk, we add non-verbal fillers: umms and hmms and breath filled spaces that serve to provide emphasis and separate one phrase from another.
When we write, we have to use syntax and punctuation in order to achieve the same kind of effect.
If you don't have them, you end up with some pretty kooky mistakes. My favorite ones are those that come about due to dangling/misplaced modifiers and improperly used commas.
I saw an accident walking down the street.
I've heard of people being described as "walking accidents," but I don't think that's the meaning here.
....aside from the small group of officers and their robot guard that had decided to make camp at the abandoned bed and breakfast that she easily dispatched.
Congratulations. That B&B will never bother anyone again.
Let's eat Grandma.
Hannibal? Is that you? Obviously, unless you're intended to actually cook and eat your matron, this would be: Let's eat, Grandma.
She finds inspiration in cooking her family and her dog.
You might recall this one from a (fake) magazine cover but, sadly, I've seen people make similar mistakes.
Do you have some favorite grammatical goofs? Share in the comments.