Unless, like a bat, you sleep upside-down, your toes are younger than your head.

Why?

Because, having spent more time slightly closer to the center of the earth, they have endured a slightly stronger gravitational field strength. This, in turn, due to relativistic time dilation, slows time down for your toes, relative to your head. With a slower passage of time during all periods when you were upright, less time has passed for them — and so they are younger.

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