This idiom or expression has to do with:

Getting out of a bad situation without being punished.

Q. Didn’t they arrest him for stealing from his mother?
A. Yeah, but somehow he beat the rap and avoided going to jail.

Also see:
Getting away with something.

This idiom or expression has to do with traffic accidents.

Hit-and-run is when you hit someone (have an accident) but you don’t stop to help or identify yourself. A “hit-and-run” accident results in a more serious punishment than if you stop.

Also see:
Hit and run.

This idiom or expression means:

Easy.
Quick.
Something that won’t require a lot of effort to finish.

A. You promised to go out tonight!
B. This won’t take long. It’s an open and shut case. We can still go.

This idiom or expression means:

Answering questions truthfully.
Going to the witness stand (in a court of law) and answering questions under oath.

As a witness you’ll have to take the stand and answer questions truthfully! Are you ready to do that?

This idiom or expression means:

The task of proving something.

The burden of proof for his innocence is on me!! I’m the one who’s supposed to prove that he’s innocent!

This idiom or expression means:

After something has happened.

You’ve already signed the contract. You can’t change it after the fact!

Your honor, the evidence was planted at the scene after the fact!

This idiom or expression like phrase means:

Something bad happening to a person as a result of something bad that the same person has done in the same (or similar) way or manner or setting. An outcome in which virtue is rewarded and evil punished, often in an especially appropriate or ironic manner.

Example:

This idiom or expression like phrase means:

Keeping quiet.
Refusing to testify.

Q. So, tell me about your date. What did you guys do last night?
A. Oh, I don’t know. I guess I’m going to plead the Fifth! I’m not saying anything.

Also:
Taking the Fifth.

Running away after being bailed out of jail and before the trial.

This idiom or expression like phrase (in legal context) means:

No challenge.
No argument.

When someone says “She pleaded no contest to the charges,” they mean:
She offered no argument.
She didn’t challenge the charges.
She didn’t admit that she was guilty, but she also didn’t say she was innocent.