The Pina Colada Song.
I absolutely love the message of this song. Two absolute scumbags looking to cheat on each other who then accidentally bump into each other along the way because they're so dishonest with each other about who they really are that neither of them is even able to recognize their own partner in a sex wanted add. And then they fall in love with the people who...who they actually are? or who they're pretending to be in the sex wanted add?....I can't tell... or whatevs. A real song for the morally bereft 70s.
Another of my favorites along those lines is "Lady Willpower" by Gary Puckett and the Union Gap. Good ol' Gar is so impressed with this woman for being able to resist is advances for so long but he's just about had enough of this crap and if she doesn't finally give in and sleep with him NOW, then he's going to stop chasing her and move on to the next one and she'll be the big loser for it. You go get 'em Gary.