Sentence:  [Regarding visiting the Indianapolis, Indiana chapter of the fraternity Kappa Sigma] … if in any respect the affair does not suit you—call at the box office and you'll get your money back or get a <WSD>rain check</WSD>, just as you please. 
Meaning of the word marked with <WSD> tags:  Any voucher or note from a merchant to a customer to provide an item the merchant has run out of at a later date for the item's current price, or (in a more literal sense) to provide a service at a later date.