A sexual peak is the time when you are having a lot of sex and it is so good - basically good sex in good quality.
According to a book by Alfred Kinsey, 'Sexual Behavior in the Human Male and Sexual Behavior in the Human Female,' men and women have different sexual peaks.
According to him, women peak in their 30s while men peak in their late teens. When men are in their late teens and early 20s they can achieve orgasm faster even without a partner but women in their age group will require a more skilled partner and peak much later. Women tend to be much older before they experience orgasms.