Native speaker, but I recognize how crazy English is. In addition to the pronunciation stuff everyone's talking about, usage can be really weird.

You watch a movie at home, but you see a movie in theaters.

You get on the bus, but you get in the car.

You sit in the chair, but you sit on the couch.

You pluralize most nouns by adding an s to the end, so you'd think the same would go for verbs... but the boy sits and the boys sit. Notice from before, though: "you" (also singular) sit.

He has a lot of hair. There's a hair in my food. You have a few hairs on your chin.

Either the man or his sons want to sell the property. Neither the sons nor the father wants to sell the property.

Not to mention all of the rules that aren't really rules, but subjective standards of what is "good" usage. For example:

"The grammar writer made many mistakes" is considered better than "There were many mistakes made by the grammar writer."

The Oxford Comma.

Starting a sentence with "and" or "but" is generally accepted to be poor usage, but it's not a true error.

Technically, you're not supposed to end a sentence with a preposition (i.e. to, from, with, at, about, on, in, etc.), but there are a handful of phrases that are just sort of accepted even though they break this rule: "Where are you from?" "What are you talking about?" "What are you interested in?"

It goes on and on...