Butt plugs are charming toys that have a recessed neck and a flare at the base, so that the sphincter muscles will close around it, and the plug will stay inside the rectum. Some plugs are better at staying inside than others, and some people prefer toys that they can slide in and out. Plugs that are more diamond-shaped, are better for staying in, while those with ripples and other textures can be fun to slide in and out during play.