I commented on a question on Skeptics.SE that it would be an interesting question whether there is a charge difference between ground and our head. The question is not very relevant, but here it is anyway: https://skeptics.stackexchange.com/questions/26942/does-putting-our-head-to-the-ground-remove-positive-electromagnetic-charges
I am not sure how far-fetched it is. I imagine there are isolators between ground and our head (shoes, socks, skin maybe??), but then again, our body being mainly composed of water is probably a good conductor.
So, is there an electrical potential between our head and ground, let's say on average? And how big is it?