In a Mail Call video, R. Lee Ermey answers a question from Zachary of Louisiana who wants to know how many gees a person can stand. Ermey is going to take us along to find out the answer of this question! He explains that g (or gee) means gravity and g-force is a way of measuring how much force is being slammed against the body of a fighter pilot or an astronaut during acceleration, deceleration, or sharp turns. There are positive gs, which push you back in your seat as you accelerate, and negative gs, which push you forward when you slam on the brakes. Its tough to measure g-forces accurately because what you feel depends on what you weigh, the shape youre in, and how the force is hitting you. Generally, you start to run into trouble around 4 gs: your heart starts to have trouble pumping enough blood to your brain; this is the point when pilots say that they cant see color anymore, known as a gray-out. Fighter pilots wore special uniforms called g-suits that regulate circulation around the legs to help squeeze the blood back up into the chest and brain. Even with a g-suit, about 9 positive gs are all the body can take.