For one thing, his cock curves up. Secondly, he's probably got his thumbs on the top tendon of his shaft intensifying the "throb". Try it -you'll be surprised how you can make your cock dance. And, if you can't, then when your dick is hard, hang a towel over it and practice preventing it from falling off - girls (& guys) love that. Knew a guy once with a little 6 incher; but he could make that thing boob and sway. With the towel, it reminded me of a towel hook. He He