The ability to wiggle individual toes
No matter how you try, you won’t be able to wiggle each of your toes in turn. That’s because only the big toe and the little toe are fitted with individual muscles, while the rest are controlled en masse by just one set of muscles. Most people in the world can easily move their big toes, but only a minority can do it with little toes.
Incidentally, some researchers advise women against marrying men who can wiggle their little toes separately from the rest: such people tend to attach too much importance to their personal freedom!