As its name suggests, a prostate stimulator is a sex toy specifically designed to stimulate a man's prostate. They are very similar to dildos and butt plugs, but they are usually curved or have a bulbous tip. The special shapes of these toys make it much easier to reach the prostate when they are inserted into a man's anus.
Some prostate stimulators may even vibrate for extra pleasure. They can be used alone during masturbation or with a partner during foreplay or intercourse.