extraconjugal
extra-conjugal
extracurricular
fornication
criminal conversation
adultery
something-something
extramarriage
mistress
number two
sow one's wild oats
free love
nonmarriageable
extramarital sex
mistressdom
hetsex
fancy woman
kept woman
mated
rumpty-tumpty
jiggy jiggy
conjugation
consummation
sestolet
pareunia
boinky
connection
act of darkness
job
humpa humpa
jigajig
throes of passion
dry sex
bonky bonky
marital embrace
intimate relations
in-out
sexual congress
go to bed with
know someone in the biblical sense
jump someone's bones
hexadactyly
fornicate
nonincestuous
unincestuous
hexadactylism
two-timing
sexennary
at it
wedding night