coitus
Scientific reference for 'doing the dirty', having a 'no pants dance', or advancing courtship. Coitus is commonly used in a popular TV show, The Big Bang Theory.
Penny: *opens door* "Hey, my power's out, can I stay here for the night?"
Sheldon: "Do you really-"
Leonard: "YES, of course...th-that's what friends are for, after all. Lending a room in a time of need."
Sheldon: "Well...as long as this doesn't end up in Leonard and Penny taking part in coitus, I guess I can live with it for one night."