shait i once did that, wasnt actually driving the rig, it was just for the thrill and curiosity (had been asking too many questions so i was given a chance to sit in the cabin)
When the truck is almost vertical and the load starts falling off, there is that slight shaking and slight backward motion and scary metal clicking nouse when the load and gravity are dragging the truck against the stop barriers, i nearly pissed on my self, actually now that i think about it, i must have passed a couple of drops.
but the adrenaline rush for a newbie, its un-matched, an absolute high, you walk out of the truck and your whole body is trembling, you can barely support your self