Alright, so this technique gives an awesome orgasm and is well worth your time. The first thing you do is get a raging erection and when you are ready to jerk off squat down with your knees and pull your cock down toward the floor and jack it. Then go until the 'point of no return' then stop wait a few seconds and go again,until you cum.
PS. For extra pleasure you have a great angle to finger your anus which will add extra sensation.