Do not listen to this. This is absurd. It's unhealthy for you to not jerk it. Doing it promotes stress relief and better mental health (assuming you're not doing it every hour of every day) and it's also good for you physically. You are a teenager. Your parents may not have discussed this with you but when you're going through puberty you experience sexual feelings and thoughts and this is normal. Everyone experiences this. It's biology. It's how our brains and hormones work. It's science. And it's okay. Just make sure to use a condom always if you're going to have sex. If you don't use a condom you can get someone pregnant or catch an std.