Butt plugs are sex toys that are designed to be inserted in the anus and rectum for sexual pleasure. In some ways, they are similar to a dildo, but they tend to be shorter, and to have a flared end to prevent the device from being lost inside the body.
Butt plugs are popular with and can be pleasurable for both men and women, both heterosexual and homosexual.
Butt plugs can be pleasurable because of their stimulation of the anus, but their main function for men seems to be to bring pressure to bear on the prostate gland, allowing them to provide a prostate massage. For women, it has been hypothesized that another source of pleasure through anal penetration is by stimulation of the internal parts of the deep body of the clitoris, although this is as yet theoretical.
Unlike the vagina, which is closed off by the cervix, the rectum leads to the sigmoid colon. Objects which are inserted into the rectum can therefore potentially travel up into the bowel: the flared end on a butt plug exists to prevent this.
In addition, the lower bowel above the rectum is easily perforated. For this reason, butt plugs tend to be shorter than dildos, and their range in size tends generally to be a variation in circumference. They must also be very smooth to avoid damaging the rectum or bowel. In order to get them into the rectum, they most commonly have a general profile of a round-ended cone which then narrows to a "waist" which locates itself at the anal sphincter, with the flared part outside the body, preventing the butt plug from slipping further into the body.
Butt plugs are often used covered by condoms for hygiene, and to allow the easy disposal of any faeces that they may come in contact with. Nevertheless, they should not be shared with other people unless thoroughly sterilized, due to the risk of blood-borne diseases, including AIDS than can arise from the transfer of body fluids from one person to another. Owing to the tendancy of latex to tear or have surface porosity, it is debatable if latex butt plugs can ever be acceptably sterilized, but silicone or metal plugs are much more resistant to high temperatures or agressive chemicals and generally can be properly sterilized with the appropriate techniques.
Butt plugs come in a variety of colors, shapes, sizes, and textures. Some are designed to look like penises, while some are ribbed or wavy. The majority, however, are made of soft jelly-like material and shaped as shown in the picture above, with a thin tip, which is slightly wider in the middle, a small notch to hold it in place once it is inserted, and a flared base to prevent complete insertion into the rectum.
There are butt plugs that "ejaculate" by squirting water, which are marketed to and are popular among gay men. There are also vibrating butt plugs, and butt plugs that can inflate and expand. BDSM practioners sometimes use butt plugs made of metal; these should be considered less safe due to the fact that they are inflexible and more likely to result in injury. There are also butt plugs specifically designed for men to stimulate the prostate. Some butt plugs are manufactured with long hair attached to the base for use in human pony play or other animal fantasy role play.
Butt plugs usually range in price from about £10 for basic models to about £20-£30 for more sophisticated expandable or battery-powered models, and up to £100 for high quality metal butt plugs.
Butt plugs can be moved in or out for pleasure; for this type of activity ribbed butt plugs can increase pleasure. They can also be worn continously for long periods of time, and some have worn them when outdoors during their daily lives. This may be part of a BDSM practice or fantasy. If wearing butt plugs and holding the anal sphincter open for very long periods of time one should take care that this practice could potentially decrease the elasticity of the anal sphincter muscles. The BMEzine risks glossary states that "The process is similar to earlobe stretch except that the 'jewelry' is not worn all the time" and that there is no harm done to the function of the sphincter when stretching is done carefully.