As its name suggests, a prostate stimulator is a sex toy specifically designed to stimulate a 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 the butt.
Some prostate stimulators may even vibrate for extra pleasure. They can be used alone during masturbation or with a partner during foreplay or intercourse.