I have a serious question about prone masturbation, as I've been doing it for my entire life. When I was young I discovered masturbation myself and didn't know the correct way to do it, I knew the majority of people did it another way, but this way just felt better and more normal for me. 1. Are there any negative side effects to prone masturbation? 2. When does the male penis stop growing? 3. I'm 19 and barely get to 5 inches when hard and was looking to fix that as well. Thanks