What Is Make-Up Sex?

What is make-up sex? Is it sex that you are having, when you weren't going to get any, to try to catch up with sex that you missed out on before? You can never catch up if you miss out.

Is it "Of course I'm not a virgin coz I've had sex" sex? You know that game that everyone played in high school.

Is it something that involves lipstick or eyeliner that shouldn't be mentioned in polite company? If caught out you wouldn't be in need of blusher.