Other things modern fighter pilots do is develop really big leg muscles through weight training. The Grunting described above is basically a flexing of the leg muscles. This combined with the constriction of the G-suit helps to keep the blood from pooling in the legs by basically giving it nowhere to go.
The F-16 also uses a steeply reclined chair for the pilot so that a high G (positive) turn sends the blood more to the lower back than the legs and gives them more of a buffer before blacking out.
In the water ball thing, what would keep the pilot from sloshing about in the liquid?
I'm Not Evil.
An evil person would do the things that pop into my head.