It's "corrupt a wish"...a bit evil but what the heck!
Someone makes a wish, and the following person grants it, but makes it all go pear shaped in some way, and then makes a wish of their own.
Example:
I wish: I was the most handsome man on earth.
Following person: Granted, but all the women drop dead.
(And then he/she makes a wish)
Got it?
Here's a starting wish.
I wish I had a million pounds.











