[Content warning: Discussion of sex toys, as well as photos of related items.]
This post has a general description of what a butt plug is and how it is used. The post contains images of plugs, but not in a sexual setting.
Butt plugs are, as the name implies, meant to be used anally. They are typically designed to be inserted and left in while other activities take place. This means most of them have a wide section, a narrow neck, and a wide base. This shape helps them stay in place. They are often a sensation enhancer, rather than something that produces an orgasm itself. Some plugs are straight, while others are curved, for prostate stimulation. Some vibrate, but many do not.
Plugs come in various sizes, so start small and work your way up as you understand your comfort range. Do not use a comfortable vaginal toy as a guide for how big of a plug you should use.
Butt plugs (and anything else used anally) should always have a wide base of some kind, otherwise you may find yourself having an uncomfortable and embarrassing conversation with your friendly local ER staff.
I’m not really going to go too far into hygiene practices here, but think about where they’re used, and you should see why you’re going to want to clean them well. You can put a condom over them, but you still need to clean them when you’re done. If you have a vagina, do not ever use a toy vaginally that has been used anally without a thorough cleaning in between. You’ll probably want to have a towel or a tissue or something like that handy when you take it out. They are not going to come out in pristine condition.
Only use plugs that are made of a non-porous material, like silicone, metal, glass, or hard plastic. Rubber or jelly or other materials can be difficult to clean and may be holding on to pockets of bacteria and general nastiness even when they look clean. If you’re using a plug made from a porous material, use a condom on it.
You need to use lube when using a butt plug. It probably won’t go in otherwise. Inadequate lube can cause irritation. Thicker lubes are generally recommended.
For people with a penis, plugs can be used to stimulate the prostate. Many people who have them find that prostate stimulation can be extremely pleasurable, but this pleasure is offset by how difficult it is to access. Some plugs have a curve or slight hook shape that is designed to press against the prostate and provide stimulation.
Here are a few images of just a sample of the wide variety of plugs that are out there:
This image is a photograph of a plain butt plug. It does not have an anatomical design. No nudity is shown.
This is a generic plug. The flared base prevents it from accidentally being inserted all the way, where it can get stuck. The narrow neck will help hold it I’m place. This is made out of flexible silicone.
This image is a photograph of a curved butt plug. It does not have an anatomical design. No nudity is shown.
This is an Aneros, designed for prostate stimulation. The curve will press against the prostate. The narrow neck will hold it in place. The round tab is meant to press a sensitive area just behind the testicles. The handle is there to make removal easier.