Guaranteed to be there
I just got back from Blockbuster Video. I noticed that AI was out, and that it was 'guaranteed to be there' or the rental is free. So I went up to the cashier, told him AI was out, and he gave me a free raincheck. Sweet!
I was really hoping to rent Ocean's Eleven but that was all out too. I picked up the movies I chose to rent, and went back to the cashier. I said, "Do you have any copies of Ocean's Eleven that have been returned?" He said, "no, but I'll give you a raincheck".
Awesome! So now I have rainchecks for Ocean's Eleven and AI. Good deal. :-)