OK, here's mine.
We had to move to a cheaper house, so we found a nice enough house to rent a few towns over. We moved in and everything was nice and we were settled. I was in my backyard one day, and I noticed that my neighbor was outside. Then I realized that it was my worst (only) enemy that I've had a bad history with for the last 4 years or so.
Of ALL the houses for rent, we happened to move in right in front of the ONE person in the entire world that I absolutely cannot stand.
Its quite irritating sometimes, but its pretty funny and ironic too.