Home run (Fourth base) is the act of penetrative intercourse.

What is the 4th base of a relationship?

Fourth base or home run. As the name suggests, the fourth base is about going all the way in your search for the big-O. It involves penetrative sex. If this is the first time for you or your partner, this is the point where you lose your virginity.

What are first second third and fourth base?

The first base refers to a relationship that involves just kissing, while the second base is when manual stimulation is applied. The third base when the relationship gets to the point of oral sexual stimulation and the fourth base is when both parties go all the way to penetrative s*x.