Rain Check

A word improperly used when trying to let someone down that you have no interest in thinking it will put them down lightly. When in reality it only ticks them off because you couldn't just be upfront and tell them No. It's improperly used because they never cash it in which is the whole point of a raincheck.

Aww how sweet, I already have plans for today with my Girlfriends I will have to put a Rain Check on that and maybe follow up.