Question

It helps a great deal to memorise idioms when the story behind forming them is revealed to learners of English. Now how did the idiom in question come about?

Answer 1

It comes from baseball - it used to be that if a game were cancelled because of rain, you could get a new ticket (or maybe reuse the original ticket, I'm not sure) and go to another game later.

Answer 2

It means I want to do that, but I can't at the moment. Can we do it another time?