Ooh, just thought of something else but not a skill so much as a weirdity and I know I'm not the only one. I once won 10/- at school when someone bet me I couldn't do it.
I can bend the distal phalanges (top bit) of my fingers while keeping the rest of my fingers totally straight.
I can touch my toes quite easily, in fact put the backs of my hands flat on the ground, so have no problem with toenails if my podiatrist isn't available.
And until I had my hip replaced 4 years ago, could do the splits.
My sons can both wiggle their eyes and it looks quite scary seeing the pupil and iris oscillating!