I can use right-handed scissors with my left hand, and I can knit in both directions without switching hands. I guess being ambidextrous isn’t totally useless (if I ever break my right hand, I’ll still be able to do most things), but it’s not really useful most of the time.

Back in uni I discovered I can titrate perfectly. Normally you have to do at least 5 or 6 titrations and average the ones that match closest, but I never needed more than 2; A rough titration to get a ballpark figure, then a second to get the exact volume. Any more after that only ever confirmed the first figure.
My professor didn't believe me the first time I came up to her and said my 2 measurements were identical, so told me to do it again in front of her. I produced the same measurement again, and she said she'd never seen anyone do that before, but I'd still have to do at least 3 measurements each time for my coursework.

Unfortunately I've never titrated anything since leaving uni.

Lockpicking. It sounds useful in theory, but being locked out of something you need (e.g. your house or some container you're authorized at work) pretty much never happens, and even if you are in this kind of scenario, there's no shot you're carrying tools on you 24/7. Still a pretty fun hobby though.

I can beat the original Pikmin game in 7 in-game days, which is very close to the limit to how fast the game can be beaten which is 6 days!

I'm strangely good at catching things intuitively (??).

Like, if my kid throws something at me, I can catch it without looking at it. Almost every time, it's fun

I can solve a Rubik’s Cube in under 15 seconds. (I had an obsessive phase as a teenager). I don’t think I’ve ever used that skill in my adult life, but they are fun figet toys for when I’m stressed.

Not entirely useless, but I can throw something into a trash can damn near every time without missing. Even if I can't see the trash can, but know where it is

I can talk just like Hoggle in the Labyrinth, and I learned the trick on how to roll the balls around on my hand the way David Bowie does in the movie.

I can spin around and around indefinitely without getting dizzy.

I can whistle really well

I can make a water droplet sound with my mouth. At first I had to flick my cheek to do it effectively, but nowadays I can do it sneakily without. Great head turner in waiting rooms 😅

No one can beat me at simon, that four color memory game. I don't remember what my high score was but I can easily get to level 60 before I start to struggle

I know the lyrics of Bohemian Rhapsody.

I can wiggle my little toes independently.

I play the drums, but not in a band or anything. It's pretty useless, but I'm glad I got good enough I could just play along with random songs and have fun at home. I didn't stick with any other instrument I've tried to learn, so I'm pretty proud of myself to still be at it after twenty years.

I'm really good at palming coins and doing variations of disappearing coin tricks. Suck at any other form of slight-of-hand but I can make a coin-sized object look like it vanished with remarkable ease and smoothness.

I can handwrite cyphered text as fast as I can write ordinarily. Never have practiced reading the cyphered text though so reading notes that I took in cypher is a pain in the ass...