Take a rain check

Rob: This is The English We Speak with me, Rob ... 
Li: ... and me, Li. Hello. (Sighs) I'm a bit bored today Rob, what shall we do?
Rob: Hmm, how about going to the library?
Li: Boring!
Rob: We could go to the cinema?
Li: Done that. I want to do something exciting. Hey, let's go to the fair!
Rob: You mean the funfair with lots of people and all those big machines to ride on? They make me feel a bit sick. Could I take a rain check on that?
Li:(Opens window) ... it's OK Rob, it's not raining, we can still go.
Rob: No Li—it's nothing to do with checking the rain—I mean, I don't want to accept your invitation of going to the fair.
Li: Oh, you're not talking about the weather. So Rob, you never want to go to the fair with me, then?
Rob: Well, I might later. If I take a rain check on something, I won't do it immediately but I would like to do it at another time.
Li: Good. OK, here are some examples. We'll see if Rob is ready to go the fair after listening to these:
If you don't mind, I'll take a rain check on the drinks tonight. Can we make next week?
Li: So Rob, if you're taking a rain check now, when would you like to go?
Rob: I think it's going to have to be tomorrow. Look, it really has started to rain now.
Li: Oh no.
Rob: Well, there's still the library ... the cinema ... 
Li: No.
Rob: OK, come on then, get your raincoat, we'll go to the fair.
Li: Oh great! You won't regret it Rob!
 (Later at the fair)
Li: You see, I said you wouldn't regret it. Isn't this rollercoaster great?
Rob: Oh ... why didn't I take a rain check on this? Join us again soon for another The English We Speak.
Both: Bye.