My sister and I had a theory when we were little: "Opposite Medicine" we called it. And it went thus: If you say one thing, the opposite will happy. This particularly counts when you're wishing out loud, though secret wishes are exempt.
So, saying in front of my parents out of the blue "Oh... Wouldn't be be terrible is we got Fish and Chips for dinner!" would often work better than asking for Fish and Chips.
I had no idea it could backfire so relentlessly on me, though.
In the middle of December I started to take extra vitamins and minerals, to bolster my immune system. A day or two later, I caught a does of the 'flu, two weeks later, I'm laid up with a chest infection.
I think I had better stop trying to look after myself; It's killing me!