It was in this novel that Erica Jong coined the term "zipless fuck", which soon entered the popular lexicon. A "zipless fuck" is defined as a sexual encounter for its own sake, without emotional involvement or commitment or any ulterior motive, between two previously unacquainted persons.
The zipless fuck is absolutely pure. It is free of ulterior motives. There is no power game. The man is not "taking" and the woman is not "giving." No one is attempting to cuckold a husband or humiliate a wife. No one is trying to prove anything or get anything out of anyone. The zipless fuck is the purest thing there is. And it is rarer than the unicorn. And I have never had one.
— Erica Jong, Fear of Flying (1973)
Jong goes on to explain that it is "zipless" because "when you came together, zippers fell away like rose petals, underwear blew off in one breath like dandelion fluff. For the true ultimate zipless A-1 fuck, it was necessary that you never got to know the man very well."