If I pierce my foreskin with a safety pin and leave it in will it be permanent then can I stretch it

I strongly advise against piercing any part of your body, including the foreskin, with a safety pin or any other non-sterile object. Body piercing should be done by a trained professional using sterile equipment to minimize the risk of infection, allergic reactions, and other complications. Piercing the foreskin could lead to significant pain, complications, and long-term damage. If you're considering body modification, it's important to consult with a professional piercer who can provide guidance on safe practices and aftercare. If you're interested in stretching a piercing, it's best to follow proper methods that involve the use of jewelry designed for that purpose, and again, a professional can provide the best advice and assistance. Your health and safety should always be the top priority.