When I played football in high school our asshole of a coach decided to give us one water break during a 2-2.5 hour practice. The next day after practice both of my legs started cramping at the same time in the weight room and I couldn't walk. Then all of me started cramping and the trainer brought me into the shower and turned it on, with the water as cold as possible. I was experiencing a full body cramp from dehydration and heat exhaustion. All of my muscles from my neck down were cramping at the same time and it was the most excruciating pain I've ever experienced. My neck, arms, back, chest, sides, stomach, hips, thighs, calves, and even my hands. I mean everything. It stopped in the shower but as soon as I tried to move it all started back up again. So I was carried to my mom's car where I was still cramping all over in the backseat while swearing in front of her from how much pain I was in. I actually shat myself in the back seat from how much pain I was in. And then I had to spend the night in a hospital with an IV in me the whole time I was there. I don't think I've ever experienced anything close to the pain I felt from a full body cramp.