Now I know what you're wondering – we're only at number 4 and what have we got: a humble household appliance.
But thinking about it, my life revolves around this pretty much essential example of white goods, just as much as its internal rotor is programmed to squirt water over plates encrusted with cement-like dried Weetabix.
For my key household chore is to empty Mr Bosch and convey his contents safely – if at all possible – to their allocated berths in the kitchen. And this must happen not once, not twice but on occasion three times a day. While other households make do with every other day and probably not Wednesday, our machine is called into action so often the poor guy's soap tray often stays shut in protest, or he throws a spring out in disgust.
I visit the kitchen with trepidation in every step: will the 'zero' be on, signifying the end of yet another cycle – and is there a mound of dirty dishes on the side, meaning it will be almost full again before long? How does a mere family of five generate more caked crockery and filthy forks than a NAAFI?
There's a clue from my wife: "If you don't want to empty it, stop eating." But there can be 10 eating shifts a day and all sorts of toys, pots and jam jars also appear on emptying – and they can go through many times, as my wife seems to be on a scientific mission to obliterate labels using a device that doesn't quite possess the power of the Large Hadron Collider.
And don't get me started on loading. When you have a vested interest, all spoons, mugs and so on go together, and plates are stacked in maximum numbers to aid rapid disembarkation and minimum operational cycles. Others are not so organised and stuff things in any which way – and why should they care. They don't empty it.
I've already done it once today, and if you look through the kitchen window at about midnight you'll see a lonely figure, doing it again.