Eating dinner with the parents last night, we were discussing a family friend who had been rained out of a session of golf and received a rain check to make it up.

Made me wonder… That’s a much more fitting use of the term than at the grocery store or K-Mart (where I think I first heard it as a child). So I had to look up the etymology…

The quick: it’s from baseball. When a game was rained out back in the day, you’d be issued a rain check. Nowadays, with the fancy barcodes and all, you just have to show up with your existing ticket. Silly technology…

Source: http://www.randomhouse.com/wotd/index.pperl?date=19990629