Ask Lemmy

Guitar picks, becaus I guitar. At least one in each rooms.

A small marlin spike. It's surprising how often I want to untie knots in all kinds of things. A marlin spike makes that easy.

Earplugs. They can obviously be used for protection from overly loud environments. They're also great for shutting out voices, music, or other noise when you're trying to read or focus on a task. I like the Loop Switch 2 plugs because they're small, versatile, and effective.

Ultralight folding bag. I carry a 19 liter bag (Nanobag Sling) with shoulder-length handles that folds down to about the size of my thumb. Any time I need to carry more things than will easily fit in my hands, I pull out the bag. It also lets me support awkward or heavy items using my shoulders and back instead of my hands and arms.

Spark plug, cause you never know when you need to break a mfer's window.

I carry around a few tampons, as a cis man.
Part of my "be prepared" strategy cause you never know what life throws at you.
On one hand, tampons are perfect kindling for starting a fire in an emergency - a wad of cotton in a water-proof hull.
But in reality, it was useful a few times already, to help a female friend out.
Or pull one apart to improvise ear plugs when a concert turns out to be way too loud.

Always keep your surveilance camera damaging laser on you at all times.

Gas jet lighter. I do not smoke. But when people ask for a lighter and I pull my lighter out, they always ask "How come YOU have a lighter?" Funny every time.

A handheld 2 way radio. The cell network is the first to go even before a disaster since the lines saturate with people calling out.

A handheld calculator and a slide rule. If the power goes out for a long time, I'll still be doing math while the rest of you chumps will be using your fingers to count to 10.

I can’t be the first person to say this, but a poop-knife.

I have a roll of dental floss in my hike bag. It's small, super strong, and there's one pile of it in a roll. Could be used for replacement shoelace, laundry line, tying wood together for a shelter, etc.

I have a dosimeter/geiger counter. So far, it's only been a neat toy for about an hour. I hope it never is more than that.

Fire extinguisher.

Get a small one and put it in your boot or the back of your ute (seppo: truck).

If you're ever first to a car accident, or have one yourself, you'll be very glad you have it.

I keep a bowling ball in my car. It doesn't make sense to have it at home.

Paracord. I use it in the house as well as with my SCUBA diving gear. If you need to tie something it's tough stuff, fairly cheap, and can be doubled up to deal with heavier loads. With SCUBA gear you can use it to create tethers for just about anything and if you have one of the camera floats that comes with a cheap little keeper strap save yourself some heartache and replace it with paracord.

An assortment of screws, bolts, nuts, and washers. Always worth having around. Some little thing breaks or you can't find one you dropped maybe the new thing you are putting together was missing one. Bonus tip, buy them at a place that sells by the pound and not the individual item. Atwoods is a place in the US that still does this that I know of but I'm sure there are a few others. Estate sales will also often have a person who will have jars of random stuff for cheap.

LEGO brick separator.

Not unusual, but surprising how many times it has come handy in group gatherings.

I have a field transfusion kit as part of my first aid kit in my vehicle, as well as in my bike kit.

So far, it hasn't been useful at all, and hopefully never will be.

I might as well go first:

Scalpels!

They have a myriad of uses. And since they're sterile, they can be used for cooking. I use them for slicing the skin on pork bellys for that nicely diced crackling - It's almost like they were made for cutting skin, or something. Besides that, they're excellent for cleaning up 3d prints. Just remember that they're supposed to be single use. While your 3d print doesn't care, your food definitely does care about how much you use the same one.

I always make sure I have a 10 pack in my kitchen.