Saw a guy who was pretty skinny, his back was as flat as a pan cake and yet he was wearing those bodybuilder singlets, the racer ones I think it's called. He was doing dumbbell curls with the most hyper extended back I have ever seen and curling the dumbbells probably and inch from the side of his legs. I looked at the dumbbells and they were 20 pounds, and he was groaning too. Never have I been distracted when in the gym but this guy really distracted me, I couldnt concentrate it was that bad. With all the info you can find on the net, never have I seen someone perform a simple exercise so poorly.