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 have unusual muscle control - I can make my eyebrows and knees dance, plus I am a regurgitator. Not as good as Stevie Starr but enough to have a disgusting party piece. I am disappointed that I never mastered the art of the flatulist.
I can make my balls dance.
Oh yeah, that too. I’ll sometimes do it when standing wait for something, like a lift. Hopefully it isn’t obvious from outside my trousers.