This perpetually work-in-progress glossary documents sexy Japanese words you may hear in Covert Japan videos or other Japanese adult videos (JAV).  Words marked in bold are so common that they're not always subtitled in our videos.  What a fun way to learn Japanese!

A
aji - flavor / taste
anaru / anaru-fakku / anaru-sekkusu / AF - anal sex

B
bakku - "back," aka doggy style
bokki - erection / hard cock
bukkake - the sexual act of covering the girl's face in semen
burikko - a girl that acts cute, naive, and innocent

C
Cheri Boi - "Cherry Boy," a guy with little to no sexual experience / a male virgin
chi-chi - breasts / tits
chikubi - nipple
chin-chin - cock / dick
chinpo - cock / dick

D
dekachin - big dick
di-pukisu - "deep kissing" / French kissing / making-out

E
ecchi - sex
eki-ben - a standing face-to-face sexual position where the guy is completely carrying the girl.  Named so as it resembles a person selling "eki-bento" lunches at the train station.
eroi - erotic / hot / sexy

F
fera - short for "fellatio," aka blowjob

G
gaijin / gaikokujin - foreigner
gaman - to endure / tolerate, as in to hold back from cumming
gokkun - cum swallowing
gomu - condom / rubber
gomu-nashi - bareback / no condom

H
hadaka - naked
hageshii - hard / intense
hajimete - first time
hakujin - a white person
hassha - ejaculation, literally "firing" or "shooting"
hazukashii - embarrassed / shy
honto? - really?

I
iku - to cum / ejaculate
irete (kudasai) - put (it) in, insert

K
kawaii - cute
kakkoii - cool / handsome
kao-dashi - cum on face
karami - a sex session
kijyoui - cowgirl position
kimochiii - feels good
kintama - balls, literally "gold balls"
kirei - beautiful
kisu - kiss
kitsuman - tight pussy
koufun - turned on, excited, stimulated
kuchi - mouth
kuchi-dashi - cum in mouth
kunni - short for "cunnilingus"
kuri - short for "clitoris"

M
manko - pussy
manpe - queef / pussy fart
mousou - to fantasize
mune - chest
mura-mura - to get turned on, horny

N
naka-dashi - cumming inside / creampie
nama / nama-ecchi - bareback sex
ne-bakku - prone bone / flat doggie style position
netorare - cuckolding (often abbreviated "NTR")

O
onani - masturbation / touching oneself
ooi - a large amount / much / many
ookii - big
oppai - breasts
oshiri - ass / rear-end

P
paipan - shaved, as in a shaved pussy
paizuri - titty fuck
pero-pero shite - lick it

R
rezu - lesbian sex

S
san-pi / 3P - threesome / group sex
seijyoui - missionary position
seishi - sperm
sekkusu - sex
semai - tight / narrow, as in a tight pussy
shimari ga ii - "good tightness" = tight pussy
shiofuki - squirting / female ejaculation
sourou - premature ejaculation / "quickie"
sugoi - great
suki (desu) - to like (something)

T
tachi-bakku - standing doggy style
tanima - "valley," refers to a woman's cleavage
tekoki - hand job
tsuyoi - strong

Y
yabai - cool / crazy / oh shit! / oh wow!  *Similar to "fuck" in English, this expression has both good or bad meanings depending on context.*
yasashii - kind / nice

Z
zengi - foreplay