When something happens when it, or something related to it, was previously mentioned. It doesn't necessarily have to be wished.
It is almost similar to "speaking of the devil".
My friend talked about her high school reunion and I told her that I haven't seen my high school friends since I graduated. The next day, I bumped into my high school friend at a mutual friend's party.
serendipity
or a a happy accident. It doesn't, however, connote that this event was previously alluded to.