This might seem ridiculous- but bear with me!
Since my brother has become obsessed with cars, he has literally spoken about nothing else. It doesn’t matter how you start a conversation, he will always steer it (pun not intended) towards cars.
So my family decided that we needed a rule to stop him from talking, before we died of extreme boredom.
After some serious thinking (i.e. two minutes of suggestions over a cup of tea), we decided that the ONLY solution was to wear milk bottle tops by licking them and sticking them to our foreheads. The rule is that whilst we are wearing them, my brother has to talk about something other than Jeremy Clarkson. It's genius really- they stay on surprisingly long and actually, it works. It really does stop the car-talk.
I know that we probably could have come up with something sensible, but hey. Now I’ve told you the story of the milk cap rule.
P.S. The Milk Cap Technique also makes for some foxy headgear (as demonstrated below)