Dude, Your friends may look cool now, but let me be blunt. Problems do not show up immediate, ok? The one thing guys care about, in particular when young as you, is whether their dick works. If you start doing this before 23 minimum, you will likely shut you body down so hard while it is still forming so badly you will not be able to be intimate with anyone! Will you feel like a man then when you have girlfriend or boyfriend (Gay-to me makes you no less of a man-or straight I really do not care.) and you are NOT CAPABLE of physical intimacy??? This is what you risking!!!! Is it worth it?
Because as one of medical professionals, if you destroy your own hormone production, there is very little I can do to help you!