I have personally tried and tested this masturbation technique and use it consistently. I discovered it after I was getting ready for a workout one day and hadn't masturbated in a couple days. First, you need a pair of spandex or some sort of spandex-like pair of underwear. I've found that Nike's dry-fit spandex to be some of the best because they don't compress too tightly, but I also use these Merona boxer-briefs that I found at Target that work just as well. The technique is pretty simple: Just put on your spandex, get an erection, and then move your erection off to the side or down your leg. Then with your hand on the outside of the material, move your erection up and down your leg. Your penis will glide against the material, which creates an awesome sensation. Sometimes pre-ejaculatory fluid can wet the spandex and create some friction against your penis, but if that happens just move to another part of the spandex.