let (it/this) slide

When someone does something wrong, and you don't punish them for it, you can say that you "let it slide". For example, if you get caught for speeding by the police but they don't want to write you a ticket, they'll say:

All right, I'll let it slide this time.

(Or at least I imagine that's true, because it's never happened to me. I always end up getting the ticket...)

In the example above, the speaker obviously doesn't have the authority to punish his coworker for not going out to drinks, so saying "I'll let this one slide" is a joke.

You can use "let it slide" (when talking about a certain action) or "let this slide" (when talking about the overall situation). As you can see from the example at top, you can also say "let this one slide".

you'd better (do something)

Saying to someone "you'd better ___" is a very strong and direct way of telling them what to do. Here are some situations where you can use "you'd better ___":

• If you're a parent, you can use it when telling your children what to do.
• You use it when you're fighting with someone.
• You can use it in a friendly situation with friends, coworkers, and even strangers when telling them to do things that are easy, unimportant, and fun. For example:

  Hey, there's some free candy over in the lounge. You'd better go get some before it's all gone!

• As in the example at top, you can use it in a joking way to pretend that you're fighting with someone or treating them like your child.

show up (somewhere)

To "show up" somewhere means to come there or to attend. Use this phrase in casual speech to talk about coming to a party or event:

Hey, thanks for showing up.

I'll (do something)

Use "will" to offer to do something, or when you've just decided to do something like in these situations:

OK. Well, I'll take it.

I'll keep an eye out for it.

("I'll" is short for "I will", of course.)

When you've been planning to do something for a while, don't use "will". Say "I'm ___" or "I'm going to ___".

We're going to keep it to just close friends and family.