I'll take a rain check on that !
What is a "rain" check anyway?

1) Is there water decending from the sky?
2) A means of restraint, check, or guidance?
3) If the monarch in question is still in power?

Makes no blood sense at all, why should any of the above result in you not participating in an event or outing?
(TwinkleFuckingToes Has a ingrown toe nail, Fri 9 Apr 2010, 9:17, 2 replies)

It comes from baseball, I believe
If a game was rained off, spectators who had paid were given a "rain check" which would entitle them to entry at a future date.
(Vice Admiral Sir Charles Cockbrush KCB MBE DSO, who is finding it increasingly difficult to log into b3ta.com wants to duck your aunt and kick your puppy, Fri 9 Apr 2010, 9:20, closed)

Americanism
no wonder I bloody hate it......

Happy Friday though and thanks for answering that one has been pissing me off for years.
(TwinkleFuckingToes Has a ingrown toe nail, Fri 9 Apr 2010, 9:24, closed)