This Saturday Morning Breakfast cereal comic reminded me of the classic time travel novel The Man who Folded Himself by David Gerrold. If you haven't read it go read it now(Amazon) to avoid the spoilers below.
In the comic above the man crassly uses his time machine to go to a time when the girl is in the mood, not realizing that if he in the present has a time machine and has this idea, he in the future might do the same thing and thus a crowd of eager men converge on the one time his love interest was in the mood. Extra humor comes from the fact that it appears to be only a single day from the evidence of all the guys at every age who appear.
David Gerrold's novel follows the life of a man whose mysterious uncle leaves him a time machine which he then uses to travel through history altering it to suit himself even as the newly created history becomes more and more bizarre. He even meets up with himself. David Gerrold is unafraid of exploring all of the implications of this and the man even has sex with himself. In the novel there is a never ending party at a house outside of time where various versions of himself are always there. In several incidents in the novel older versions of the man keep propositioning younger versions of the man for sex, much as in the story in the comic above.
The time travel device has ended up creating many alternate versions of history and thus create many different versions of himself. At one point he even meets an opposite sex version of himself.
Gerrold's novel is complex and bizarre and very interesting. I invite you to read the novel and count how many characters are in it.