I bet (clause)

Saying "I bet..." is a casual way of guessing about something. You can use this in all kinds of situations where you are guessing about something and want to compare what you think with what other people think:

I bet there'll be a lot of traffic at the beach this weekend.

I bet you can't guess what just happened to me.

I bet the meeting this afternoon will be pretty short since David's not here.

whatever

Use the word "whatever" when you're annoyed by what someone has said but don't want to continue arguing with them. It sort of means "I don't agree with you, but I'm not going to talk about it any more." For example:

A: You were so rude to me.

B: No I wasn't!

A: Yes you were. How can you possibly deny it?

B: Whatever.

This phrase can be pretty rude depending on your tone of voice and who you're saying it to.

use a (pickup) line on (someone)

A "pickup line" is something that you say to people who you're attracted to, to start a conversation with them. Pickup lines can be simple, like this:

Hi, what's your name? I'm Patrick.

There are also a wide variety of clever or funny pickup lines that people make up, like:

Heaven must be missing an angel, because here's one right here on Earth.

When someone uses a pre-written pickup line or repeats the same introduction to multiple people, you can call that "using a line":

He used some cheesy pickup line on me. I just rolled my eyes and turned the other way.