I've never found that in the Bible.
Also, what constitutes sex?
I Corinthians 7 speaks of this:
5Do not deprive each other except by mutual consent and for a time, so that you may devote yourselves to prayer. Then come together again so that Satan will not tempt you because of your lack of self-control. 6I say this as a concession, not as a command. 7I wish that all men were as I am. But each man has his own gift from God; one has this gift, another has that. 8Now to the unmarried and the widows I say: It is good for them to stay unmarried, as I am. 9But if they cannot control themselves, they should marry, for it is better to marry than to burn with passion.
Christ speaks of marriage as a unity in the flesh:
Mark 8:
6"But at the beginning of creation God 'made them male and female.'[
a] 7'For this reason a man will leave his father and mother and be united to his wife,[
b] 8and the two will become one flesh.'[
c] So they are no longer two, but one. 9Therefore what God has joined together, let man not separate." 10When they were in the house again, the disciples asked Jesus about this. 11He answered, "Anyone who divorces his wife and marries another woman commits adultery against her. 12And if she divorces her husband and marries another man, she commits adultery."
And you would think that is just marriage but Paul knows that sex is essentially considered becoming one flesh with someone:
1 Corinthians 6:16
Do you not know that he who unites himself with a prostitute is
one with her in body? For it is said, "The two will become
one flesh."
It is covered thoroughly in the Bible though French kissing is not.
How to define sex? Well, as the Bible is not a dictionary I do not know. I imagine that their idea is genital-on-orifice contact. I am still not sure what Bill Clinton's definition is, though. I am not even sure what his definition of 'is' is.