Ass

Ketsu

Dembu (a politer form, analogous to the English derriere or posterior)

Shiri (politer yet, especially among women. Analogous to bottom)

Oshiro (normal use)

Anal Sex

Anaru sekkusu

Asshole

Ketsu no ana

Kikuza (means chrysanthemum, similar to the English term rosebud; old slang)

Asshole
(As insult)

Kusottare (literally, "Shit-drip")

Kusoyarou (literally, "Shit-man")

Kora! (Rough, as in "Hey asshole!" Roll the R for more effect, and say quickly.)

Attraction

Tamaranai, Tamannee (an uncontrollable compulsion)

Balls, Testicles

Kintama (golden balls)

Bondage

Shibari, Kinbaku

Boyfriend

Boifurendo (from English); Kare (a girl's lover)

Breasts

Mune, oppai, chichi

Buttocks, Buns

Shippeta

Condom

Gomu (from gum); Kondo-san

Cunt-print

Paint india ink on a woman's cunt, and press into a piece of paper...

Dildo

Baibu
Dendou-kokeshui (Almost all Japanese dildos are motorized)

Dirty Old Man

Ero-jiji, Ero-oyajii

Dyke, Lez

Rez

Dyke, bull

Otoko onna, or "man-woman"

Enema

Kancho

Erection

Pin. This is a playful term. "Binbin-daze" is an affectionate name meaning "Mr. Boing Boing" in reference to a young man's penis that is always on the verge of erection.

Erection,
becoming hard

Tento-wo-haru (Make his penis hard and lift up his pants like a tent.)

Expose

Rosyutu-Purei

Faggot

Okama
An effeminate homosexual is "neko." Neko means cat in Japanse. This word may also also mean a femme dyke. Neko yaru, or"doing cat" is a synonym for gay sex, or sometimes kinky sex between hets.

Fellatio

Kyande (from candy); fera, ofera; fuefuki; shakuhachi (from old style Japanese flute)

Femdom

Joken

Foot Fetishist

Ahi-fechi (from fetish)

Fuck!

Kuso! Used as an interjection, like "Shit!" or "Damn!"

Fuck me!

Hamete chodai! (please put on)
Irete! (Insert)

Fuck me hard!

Fukaku hamekonde chodai!
Uuume Mecyakucya ni shite!

Gay

Gei (from English, obviously)
Bara Zoku (Rose Gang or Family)

Girlfriend

Garufurendo; suke (slang)

Hardcore

Hado koa (used in the gay community)

Humiliation, mild

Shuchi pure

"I'm coming!"

Iku...Iku!

Jerkoff

Masutabeshan (from masturbation)
Masu-wo-kaku

Kink

Hentai

Lesbian

Rezubian (from English)
Riri Zoku (Lili Gang or Family)

Lesbian Sex Show

Rezpurei (lesbian-play, performed chiefly for Japanese cross-dressers)

Lesbian Sex

Kaiawase (literally, cunt-grinding)
Rezuru

Lover

Aijin (adulterous affair); koibito (normal use)

Masturbation, general

Hitorigokko (self-play)
Hitori-ecchi (self-sex)

Masturbation, male

Senzuri (a hundred rubs)
Shiko shiko

Masturbation, female

Manzuri (ten thousand rubs)
Suichi o ireru (flicking the switch, or fingering a clit)
Onaru (play on onanism)

Miuri

Sold herself for money (into bondage)

Penis

Chinchi, chinko, chimpo, chimpoko (cute terms analogous to pecker, dick, willy, or wee-wee)

Penile exposure

Furuchin (wagging penis)

Pervert

Hentai
Chikan (men who fondle women on Japan's notoriously crowded commuter trains)

Prostitution

Enjo kosai (money-for-sex)

Prostitute

Pan-pan (used by GHQ)
Abazure (literally, "saucy old woman" but has a modern reading as a noisy slut)
Baita (means sale-woman, or whore)
Yoruno-Onna (Night-girl)
Yotaka (Nighthawk)

Pussy, Cunt

Omanko, omeko, manko
Haka ("Box." This is self explanatory. A local slang.)

Rape

Gokan

Raunchy

Eroi (from erotic); echi (From H, the first letter of hentai.)

Scat games

Unko pure (I think the pure comes from English play)
Ogan pure (Ogan = gold, sometimes this is the color of excrement.)

Schoolgirl

Kogal. A "high school gal" who is willing to trade sex for money.
Jyogakusei. A normal schoolgirl.

Sex

Ecchi (again from "H.")

Sex Tape

Ero kasetto

Sex Slave

Joro (woman sold into prostituition)

Sixty-nine

Ainame
Shikusu-nine (from English)

Slut

Yariman. Means "Doing-it Manko" or "10,000 time doing-it." Well known as one of the dirtiest words in Japan. Unlikely to see in print.

Spank

Oshiri o butsu/tataku (normal use)
Ketu-bann (ass-bang)
Shiri-tataki (hit ass)

Stud

Iro otoko

Training (sexual)

Chokyo

Transexual

Futanari

Tits

Chichi

Tit-fuck

Paizuri

Urine shower, facial

Gan-men Shawaa
Seisui-purei