Keys - house, office and car - are tiny tools we use everyday. Loosing or breaking one slows you down and is often expensive. Make yourself spares
(multiples!) now, and you can thank me later.

Keep a spare with your dear wife, wallet, in a desk drawer, man purse, clipped to your jacket or with a neighbor.

Agree entirely.
I have seen so many people put to considerable trouble and expense for want of a spare key.

I carry two sets of important or frequently used keys, one set in trouser pocket, the other in a bag.

A spare key to my office and workshop at work is hidden elswhere in an extensive building.

A few years back I lost my keys while crossing a street. My luck being what it was, they were driven over! Not once, but 5 times, it was a long line of cars.

While keys are made of metal, it is very brittal, I ended up using my spare keys that I keep in my wallet to get home and in. Luckily I had a truck at that time that didn't use the chipped keys so I could cut off the plastic.

If you have a car that uses a chipped key, the trick I like to use is to have a spare chipped key hidden. One idea is to zip tied under the passenger seat somewhere. and keep a cheap normal key that will work the door locks to get you into the car.

It is cheaper to have the chipped key made once, than to have someone technician come out and program based off your VIN number or something.

I don't like to carry spare keys on me or in my bags. Too easy to loose them or getting stolen. I do put spare keys in hidden keysafes with number locks.

The voice of recent experience?

The big one is to make sure you buy the third key from the auto dealer when buying a car. If you lose one encoded key, it costs a small fortune to get a replacement made because you need to have 2 encoded keys at all times.

I've heard that some insurance companies won't pay out on auto theft claims if you don't have all the sets of keys for the car. I've never had a car stolen from me and it's hard for me to imagine my insurance company treating me so badly, but it's something to look into if you do decide to keep a spare key in your car.

I've never understood the term man purse. Exactly what is that?

Just a purse, but for man. Sometimes referred as a 'murse'. Little shoulder bag thingy.

The Gaffer's Bag is not a Murse, no shoulder strap. It's just a tool bag -- define "tool" however you find convenient.

As for spare keys, my spare (third) truck key is in my Mission Wallet. No need for a spare house key.

I love my Gaffer's Bag; it's used for holding loose 9mm ammo when going to a match or range practice.

Spare key for my house is hidden inside my garage. My garage has a keypad remote, so as long as the power is on I can open my garage door, shut it, and then fish the spare key out from its hiding spot and get inside.