Coitus: Origin, Latin, from past participle of coīre, to copulate.
Mammaris: Origin, mammary 1682, from French mammaire; from Latin mamma "breast," probably from the child's word for "mother."
Fairly well, old chap. Muffy said she was in her "scarlet phase". So, after the cotillion, we did a little coitus mammaris in the back of the Bentley behind the clubhouse. I was a tad annoyed when she used my ascot to clean her "pearl necklace" off.