PHRASES AND IDIOMS
rain check: (idiomatic) In social interactions, a polite way to turn down an invitation, with the implication one is simply postponing it and that another time would be acceptable.
I can't go with you to the museum this Saturday, but can I take a rain check and go some other day?
The expression may have originated in the era of open-air markets where the occurrence of significant rain usually required a vendor to pack up their goods and leave. The term may also be based on the issuing of tickets to claim property such as a coat or hat check. Before 1889, US baseball fans were issued a new ticket if rain was heavy enough to cause a game to be postponed. Abner Powell added a detachable stub called a rain check that year. This quickly became a standard practice for all major league teams.
rain check (on something):
a reissuance of an invitation at a later date. (Said to someone who has invited you to something that you cannot attend now, but would like to attend at a later time. *Typically: get ~; have ~; take ~; give someone ~.)
We would love to come to your house, but we are busy next Saturday. Could we take a rain check on your kind invitation? Oh, yes. You have a rain check that's good anytime you can come by and visit.
-Ramesh Chandra Khankeriyal