what causes people to be horny?

One word: Hormones.

At a certain age of a boy or girl’s life, the body begins to react differently. Boys, after they mature and their penis is no longer that of a child’s, reacts to the blood flow within a boy’s body. For example, if a 19 year old boy sees his girlfriend naked for the first time, his brain will send signals to his body to produce more blood; the extra flow of blood will cause his penis to enlarge and harden, thus causing an erection. This is supposed to be for sex. Obviously, seeing isn’t always enough.

Touching, especially for a girl, is important. Gentle or tickling sensations will cause a boy to get hard & a girl to start getting “Wet”. When a girl gets wet, it means her vagina is producing its own lubricant for the experience of sex. If a woman is not wet enough, or if there’s not even lubricant, it can really hurt when the penis penetrates the vagina.