The term Taking A Rain Check is used when declining an invitation on one day, but keeping it open for another one. The phrase originated in the 19th century, when American baseball clubs noticed crowd levels dwindled during the winter months. They realised that fair-weather fans were not interested in games played on cold or wet days, particularly if there was a chance of bad weather stopping play. Then, someone came up with the idea of promising a "rain check" (i.e. a rain ticket) to any fan who wanted to leave (up to a certain point during a match) because of bad weather. The "rain check" was good for both fan and club and the practice spread until it became common for American baseball fans to "take a rain check" halfway through boring games, whatever the weather.