When a guy gets excited blood flows into his penis, causing it to increase in length. It becomes stiff and stands up: he has an erection. Once a guy has a hard on he can have intercourse.


How does it work?
Four stages of a hard on
Spontaneous erections
Nocturnal erections

When I get a hard on it stands straight up. Is that normal?
I think my boyfriend’s penis is broken. Is that possible?
My boyfriend gets an erection when we kiss. Does he want to make love?
When we wanted to make love I did not get a hard on. How come?

See also: morning erections, erection problems