@shebang @fluffy
Men are usually better at picturing geometric shapes in their minds and intuitively manipulating them, such as rotating them, and figuring out how they would look.
It's not that women don't understand gravity, it's that when given that task, women are less likely to imagine the water bottle rotating in their mind so they don't intuitively notice how the water would react. Such a person would have to consciously think about the influence of gravity, and basically waste time doing so. Meanwhile, I was wasting time trying to figure out how high the water would end up in the rotated bottle, because the shape the water takes is different now.