Recently started using mail merge.
Combined it with some vba scripting(didn’t learn it well, just found some scripts on the net and modified them a bit) so that I could get pdf files for emailing by clicking a macro button from an excel sheet.
Also, go to use the info about the keyboard mouse right click button when someone’s Right Mouse Button was not working. https://www.online-tech-tips.com/wp-content/uploads/2020/04/Windows-Right-Click-Button.jpg
I mentioned only computer things because of recency, but please do share your experiences in other topics too.
For people with physical jobs, try a little weight lifting. You don’t have to be the best or lift super heavy weights for it to be useful.
It’s one thing to have signs up at work reminding you to lift with your knees. It’s another thing to really learn, through constant practice, how to move your body safely, and activate muscles you never thought about. You won’t need signs to remind you, and you’re less likely to lift something stupidly and fuck up your joints even if you’re in a hurry, because correct technique will be burnt into your brain.
I know it’s not exactly obscure knowledge but a lot of people don’t bother unless they’ve got some kind of body goal. I’ve found it to be an educational experience even if I’m not a bodybuilder.