What is something small that you learned recently?

Hit me with anything at all that you found interesting, fun or motivational from your recent studies.

I'll start:

I recently learned the word 在来線 – conventional line – to conveniently refer to pretty much any passenger train that isn't a bullet train. Very handy. I like trains and I feel like now even saying 'conventional line' in English instead of 'local line' is going stop any confusion.

Also upon the discovery of カフェインハーフ coffee in the office, I learned that カフェインレス does not mean "coffee with less caffeine in it" but literally "caffeineless coffee" aka decaffeinated coffee… It should have made sense when started feeling like I was immune to the effects of three cups a day.