http://4jndbnscrvmljnl3vynggebzvi5saz5gllk3iksdskgkmoq5oaqtxrqd.onion/x/index.html
For anyone who isn't an addicted coomer, I don't recommend it. Have sex with a woman you care about and let yourself finish. That's probably better for you, physically and psychologically, than semen retention or masturbation.