The phrase to issue a rain check means to postpone an event or agreement indefinitely to a later date with a commitment to renegotiate then. It has its origins in the United States. In the United States, if a sporting event had to be postponed because of rain, the spectators or fans who had booked tickets for the event would be given tickets which would allow them a free ticket for the same event which would be held at a later date. These tickets were called Rain Cheques. And with the passage of time, the expression was born.