Ask Lemmy

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

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.

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.

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.

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

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

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.

Donegan OptiVisor Headband Magnifier - https://doneganoptical.com/product/optivisor/

with optiloupe - https://doneganoptical.com/product/optiloupe/

and Quasar LED lighting attachment. https://www.esslinger.com/led-visor-lighting-system-attachment-for-optivisor-headband-magnifier/

I originally got it when I was doing a bit of electronics work. But every couple of months there'll be times when I really want a hands-free magnified view of something I'm working on, even if it's just for a household chore. There are plenty of cheap knock-off out there, but I believe this is the original. I was at the Intrepid Museum in NYC and there was a photo of a NASA engineer wearing one of these.

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

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.

LEGO brick separator.

Nail clippers. Small but powerful penlights.

I keep a Windows 11 installer USB on my person almost at all times. I've had to perform an impromptu utilman.exe trick (consensually) multiple times. (Replacing the ease of access menu EXE with a command prompt somehow still allows you to get an administrator CMD window on the lock screen, even in 2026).

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.

Radiator bleed-screw tool on my keyring.

I'm a plumber by training.

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

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.

I have no logical reason other than I like it but I have my keys on rings that are on a actual climbing grade carbiner and then on the keyring I have a thing from the internet that can sharpen knives and has a ferro tod and a whistle. then a can opener thats swag from some conference.