get in an accident

The phrase "get in an accident" usually means to have a car accident.

"Have an accident" is another way to express a car accident:

I had an accident.

But this phrase can also be used for a lot of other situations, including peeing in your pants. But the phrase "get in an accident" almost always means to have a car crash.

mess up (something)

To "mess up" something means to break it or make it ruined. The word "break" is used for things that break into separate pieces, or machines that don't work any more. But "mess up" can be used for a wide variety of situations. For example:

• mess up a project
• mess up your relationship with someone
• mess up someone's car
• mess up someone's face (by hitting them and giving them bruises)
• mess up a recipe that you're cooking