Vibrations on and around tip of penis.

Masturbation is an act which is done till ejaculation. If you have food, it satifies your hunger, but do you keep on eating it or licking your fingers for hours? Same with masturbation. At ejaculation let go of your penis. Let it rest for a while. No one masturbates for hours. Its a BAD HABIT and this will make things worse for you. If you get erect again it is because you are not allowing the penis to rest. Erections happen due to increased blood flow in the penis. A man gets an erection at many occasions when blood flow to his penis increases, like at passing motions, at exercising, even during sleep 3-4 erections happen. So getting an erection due to a constant masturbation is NOT correct. it will make the penis store blood for a longer period and this may cause the blood to stagnate and lose oxygen. Thus depriving the tissues of your penis with oxygen. So once you masturbate and ejaculate. do not touch your penis. You yourself say it a bad habit, then why not break it.

Masturbate only when you are aroused. Habitual masturbation is BAD and it can cause harm to your penis