A person that lives a life of promiscuity is someone that's considered 'promiscuous' - meaning they are very sexually loose and not at all bothered about remaining loyal to one sexual partner.
E.g A man that can't go to a bar without ending up sunk to the nuts inside someone else by the end of the night, or a woman that can't keep her legs closed and hands sex out on a platter to others. A slut, basically.
Also the name of a 2006 mainstream song by Nelly Furtado featuring Timbaland.
"Promiscuous girl, you're teasing me!"
Damn yo, Mike can't stopflirting with chicks behind his wife's back, man is way too promiscuous!