Something you’re just good at with minimal effort and/or you learned much more quickly than average.
For me, it’s paper snowflakes. My brain just seems to effortlessly figure out what cuts to make to the paper wedge to make it turn out exactly how I want it. Largely useless, but good fun and was a much-needed ego boost when I was a kid :]
I can do this as I’m drinking something - one gulp is roughly one ounce. Was especially handy with water fountains when tracking my hydration, but that hasn’t been relevant since 2019.