In 2007, famous "car guy" Jeremy Clarkson announced to the Top Gear audience that he had learned something that morning that he found so astonishing he had to test it. It's an oft-repeated claim, spread more like urban legend than actual fact: You can extend the range from which to lock or unlock your car simply by holding your key fob to your head.
But why does it work? As it turns out, there's a different YouTube video featuring a physicist explaining that.
To make a long story short, holding the key fob to your your head turns it into a temporary antenna, taking whatever signal was present and amplifying it. This works because of how water interacts with electric fields — and especially nicely with heads because of how much water they contain (around 73%, according to Healthline).
An experiment conducted by a user on the Physics StackExchange forum was able to further clarify the best position for the key fob: pressed up against the temple of the head. Although the technique is completely safe, the user also reported the best method that didn't involve putting the key to your head: pointing your remote directly at the car at an average body height. Citizen science at it's finest.