Well, negative g's are not very pleasant beyond the initial weightless feeling--bursting blood vessels and all that. Positive g's knock you out long before any real damage.
The body can sustain more acceleration perpendicular to the spine than parallel with it. The originator of Murphy's Law, John Stapp, withstood 46+ g's in a rocket sled back in the late 40's. I'm sure you'll like Stapp's Law:
"The universal aptitude for ineptitude makes any human accomplishment an incredible miracle".
http://en.wikipedia.org/wiki/John_Stapp

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