The term "erection" is most often used to refer to an erection of the penis. A man's penis is usually soft, quite short and hangs down. When the penis is like this, it is said to be flaccid (). In order for the man to take part in sexual intercourse by putting his penis inside a woman's vagina, his penis needs to become longer, thicker, harder. For many men it stands upright. It is okay if it points out or down. When the penis is hard, it is said that the penis is erect or that the man has an erection. The scrotum (the bag containing a man's testicles or "balls") will usually tighten during erection. The penis usually needs to be at least mildly erect before the man can have an orgasm and ejaculate semen.