a (sales) pitch

In sales, your "pitch" is what you say to people to introduce your product or to get them to buy something. It's about 30 seconds to 5 minutes long. A salesperson's pitch is usually the same, or very similar, every time they talk to a customer. You can use the word "pitch" as a noun, like in the example at top. You can also use it as a verb:

Could I come to the next Directors' meeting and pitch my idea?

There are other kinds of "pitches" as well. For example, a writer might have to "pitch" an idea for an article to an editor. At a television studio, a TV show creator "pitches" the idea for the show to the television executives.

go in there and (do something)

People use the phrase "go in there and ___" to talk about some bold or exciting action that takes place in a room. For example:

Just go in there and tell her what you think.

This means to go into a room (maybe someone's office) and then tell someone your opinion. A lot of times, when people use this phrase, "in there" means an office or meeting room. Here's another example:

He went in there and told those lawyers that if they had a problem, they could take him to court.

hit (someone) over the head with (something)

"Hitting someone over the head with ___" is an idiom that means to repeat something again and again. For example:

After the second or third time she said it, I was like, "All right. We get it. You don't have to keep hitting us over the head with it."

"Hitting someone over the head" with an idea is usually a bad thing.

a pre-rehearsed (speech)

When someone says something that they've already practiced several times, you can call their words "pre-rehearsed".

We often use the phrase "pre-rehearsed" to complain that someone isn't speaking honestly or naturally. For example:

All they do in those presidential debates is read out pre-rehearsed speeches. They never actually answer the questions.