Vibrator (device designed to stimulate a woman's genitals).
Back-of-the-book; denoting those stamps in a catalogue that are not used for the payment of regular postage fees, and are displayed separately in the catalogue after that listing; the division between these two groups varies with the publisher.
Sexual intercourse in general; sex.
Sexual intercourse by people who are not married to each other, or which is considered illicit in another way.