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.
A session of masturbation.
To masturbate.
To indicate that someone (normally the speaker) is either masturbating, or inspired to by sexual arousal.
Pornography.