Much like George Carlin's Incomplete List of Impolite Words (a personal favorite available here), this is not intended to be a complete lexicon of sexual terms and definitions. Instead, let this be an aide in understanding some of the words you may encounter on this site.
Dirty Sex Dictionary is a great resource
Anal Beads: A class of sex toy consisting of balls of various size strung together on a string or a flexible rod. Pleasure is not as much derived from the insertion of these beads, as from their extraction. Despite how tempting it may be, anal beads should not be ripped out with the same enthusiasm with which one yanks the cord of a lawnmower. Synonyms: Chinese/Oriental love beads, string of pearls, siamese strings.
Anal Bleaching: A cosmetic procedure in which chemicals or lasers are used to lighten the darker skin around the anus in order to make it match the lighter skin of the buttock. The process originated with female porn performers before seeping into mainstream populations in the early 2000s with the rise of free, online porn.
Analingus: Oral sex performed on the anus. Synonyms: ass blow, blow some ass, clean the kitchen, lick the fudge bowl, lick the jar/bowl clean, rim job, rimming, suck asshole, sugar bowl pie, toss the salad,
Anal/Ass Sphincter: Two muscles consisting of an outer and inner sphincter that keep the anus closed. These are the muscles that must be relaxed during anal sex. These are also the muscles that must be surgically repaired after extreme anal play.
Ball Gag, Gag: A mouth gag in which a ball-like object is tied into a person's mouth to prevent them from speaking or screaming. Many ball gags come with a hole in the center to facilitate breathing. A common sex toy in BDSM play.
Bareback: Risky sex without a condom. Synonyms: apache
BBC: “Big black cock.” Used in personal ads and in porn.
BBW: “Big, beautiful woman.” Used in personal ads as a euphemism for fat.
BDSM: “Bondage, discipline, and sado-masochism.” A catchall term for fetish play.
Blumpkin: Fellatio performed while a man is defecating. Often used in fetish play as a form of degradation.
Bondage: Fetish play in which a submissive partner is physically restrained.
Bondage Babe: A woman dressed in fetish gear, including latex, fishnets, collars, or PVC. Often refers to a woman who is more into fetish as a fashion than a lifestyle, or a fetish model who only participates in fetishistic acts for pay.
Bugger: Anal sex or bestiality. In the UK the term is similar to sodomy in that it is a catchall for deviant sex.
Cage Fetish: A fetish for being confined to a small space. This often manifests as a sub being locked in a cage, box, or a closet. The caged sub is then teased, taunted, tortured, and/or ignored by the dom.
Chick-fil-A: When a man is penetrated anally by a dildo, usually worn as a strap-on by his female lover. Synonyms: pegging. Usage: “Her boyfriend’s kinda homophobic, but I hear he loves Chick-fil-A.” Origins: Dan Savage's sex advice column, Savage Love.
Choker: 1. A large penis. 2. A collar often worn in the BDSM scene to signify ownership in much the same way a wedding ring does in the vanilla community. These collars are often used on submissive partners during fetishistic acts.
Clitoris, Clit: the bundle of nerve endings at the hood of the vagina that can produce anorgasm when properly stimulated. Some men believe it to be a myth. This is also the part of a woman’s anatomy that grows into a micro-penis when she experiences an influx oftestosterone from steroids or a hormone imbalance. Porn star, Vanessa Del Rio, was notorious for her enlarged clitoris after she took steroids to build muscle. Synonyms: button, man in the canoe, nub
Cock and Ball Torture, CBT, C & B Torture: A type of sadomasochistic play in which a dominate partner inflicts various types of pain on a submissive partner, who is typically restrained during the session. The type of torture is only limited by a dominate partner's imagination and can involve any number of things: stomping, flicking, pinching, burning, clothes pins, scratching, stretching, piercing, pulling, shocking, flattening, nailing.
Cock Ring: A ring that is slipped over an erection to the base of the penis in order to slow the loss of blood, thus maintaining an erection longer. These sex toys are made out of a variety of materials, including metal and rubber.
Cowgirl: A standard sex position in which the woman rides atop the man who lies flat on his back.
Cuckold: 1. A man whose wife or girlfriend has sex with other men. 2. A fetish in which men enjoy watching their female partner having sex with other men, particularly men who are more physically imposing. Synonyms: cornuto. Origins: From the cuckoo bird, which changes mates frequently and lays eggs in other birds' nests.
Cupping: A type of sadomasochistic play derived from a healing practice in ancient Chinese medicine. Typically the dom uses a flame to remove the oxygen from a glass cup. The cup is then quickly placed on the sub's skin. The vacuum sucks the skin into the glass, creating a large, hickey-like mark.
Deep Throating: When a penis is jammed down a person’s throat during fellatio.
Diaper Fetish: A common prop incorporated into age play or fetishes for infantilism, scat, watersports, humiliation, dominance, helplessness... Some believe this fetish develops early in life, when a child associates diapers with being loved and coddled. Extreme diaper fetishists make themselves incontinent so that they need to wear diapers constantly.
Dildo: Any phallic object used to penetrate the body in order to achieve sexual pleasure. Usually a sex toy made out of rubber, plastic, or glass. A dildo can be a vibrator, but not all vibrators are dildos. Generally though, dildos do not vibrate.
Dirty Sanchez: When a man pulls out from anal sex and wipes his dick on his partner’s upper lip, giving her a thin, shit mustache.