Fauteuil d'amour

Which means, more or less, "armchair of love," and this is it, even if, as Sean Thomas writes, it looks like "a commode for an incontinent Chinese warlord."

Edward VII apparently had a contraption like this designed for use with threesomes and moresomes, which I suppose is further evidence that it's good to be the king. Me, I can't imagine either the logistics or the trigonometry.