(do something) as soon as (something happens)

The phrase "as soon as" expresses something that happens immediately after something else:

He called as soon as he heard the news.

I went straight to sleep as soon as I got home.

Another way of expressing a similar idea is "when":

I'll start dinner when I finish writing this e-mail.

But you use "as soon as" to emphasize that you're doing it as quickly as you can. So this phrase is useful in situations where you're making an excuse for being late.

(someone's) heart is racing

When your heart is beating really fast, you can say that it's "racing".

Your heart can race when you're scared, nervous, excited, or when you have some kind of medical problem.

One other thing that can "race" in this way is your mind:

As soon as he said he needed to talk to me, my mind started racing, wondering what it could be about.

This means to think quickly and nervously.

uh oh

English speakers say this when they notice a problem. 

Uh oh. We’re out of milk.

Uh oh! They’re closed!

"Uh oh" is innocent-sounding. Children use it as well as adults.

What could (something) be about?

When you receive a tiny bit of information, or you see or hear something, and you want to know more, you can say this.

 What could all that commotion be about?

A: There’s a notice in the elevator saying people need to review the building policies.

B: What could that be about?

like, “(something someone said or thought)”

Say “like” to informally communicate someone’s words or thoughts:

She told me I was being unfair, like “You let everyone else do it but not me.” 

I was just sitting there, like “Am I the only one who thinks this is nuts?”

A more common version of this is with a subject and a be-verb. We use this more to talk about someone’s words:

I was like, “Can I get some extra napkins, please?”

I showed her pictures from the party and she was like, “Look at those girls and their short dresses!”