Butt Plug - Much like a dildo, but usually pear shaped with a flared base.  The flared base prevents the plug from being lost in the anal cavity; the pear shape holds the plug in place. Butt plugs come in a variety of sizes and may have a variety of features, such as the ability to vibrate.  Butt plugs can be made from a variety of materials and come in a wide variety of colors and styles.