The ejaculation of semen from the penis is the culmination of sexual intercourse in men. It makes it possible for his female partner to fall pregnant. Ejaculation may also be stimulated by masturbation.
The man feels a build up of pressure in the base of the penis and testicles. Then with a release of pressure and pleasure, the semen is forced down the urethra by contraction of the seminal vesicles in the groin and the muscles at the base of the penis. Ejaculation may last in an intense phase for ten to thirty seconds, but semen may leak from the penis for some minutes afterwards. The penis usually becomes flaccid and soft shortly after ejaculation.