Hi, thanks for your question in HCM. Coming to your concern, if you feel that the skin of your penis or scrotum is getting cuts after masturbation, kindly check if you have sharp nails. Have you recently shaved your private parts? Cuts may happen while shaving but it goes unnoticed while shaving. And if you have not shaved, sometimes pubic hair too causes some scratches or minor cuts due to vigorous rubbing or friction during masturbation. If there is any burning sensation or pain on the cuts, applying soframycin ointment and keeping the area clean will heal the cuts in a week. If there are some blisters, itching, pain, bleeding, foul smelling, then kindly visit your local doctor for further investigation and treatment. I hope the above informations are helpful to you. Take care.