Human penis
Orgasm and ejaculation can happen during many types of sex acts including anal and oral sex, and when masturbating. A condom should be used during anal sex to avoid getting a urinary tract infection. Masturbation can include touching and rubbing the penis and other sensitive areas of the body, such as the scrotum, and other places in the genital area. This can be done naked or through clothes. Sometimes the penis is squeezed between the partner's thighs without being inserted into the body. This is called intercrural sex. Sometimes the penis is rubbed against the other person's body. The people can be naked or wearing clothes. When two males rub their penises together or against each other's body, it is called frottage. Ejaculation may also happen without touching during sleep (called a 'wet dream'). This is common, especially for pre-teen and teenage boys. It is uncommon in adults. While it can feel almost magical to ejaculate during a dream, boys don't like the mess it creates. Boys usually don't have wet dreams if they masturbate before sleeping every night.  A male must have started puberty before he can ejaculate. (Sometimes when a boy who has not started puberty masturbates, a small amount of urine comes out.) During orgasm, muscles push semen from the penis. Semen moves through the urethra and comes out of the hole at the tip of the penis.