Here's the japanese terms/words your parent dont want you to know...
ahou- fool
atama wari- literally bad head, thickheaded
baka- idiot, stupid
chichi- vulgar term for breast
chinpo- vulgar term for a male's

damaru- to be silent, damate- will be silent, damare- shut up
dame ningen- literally worthless human, failure
doji- clumsy
hage- blady
hentai- pervert
kimoi- slang for kimochi warui(feels bad), gross, creep
kisama- "you!" vulgar term
kusai- smelly, foul
gomi nushi- litterally trash owner/master/lover/god, means filthy like a dung beetle
mazo- slang masochist
omanko- vulgar term for a girl's

sado- slang sadist
saitei- worst, pathetic
seikou- can mean sucess or intercourse (therefore dai(big) seikou can mean huge sucess or...fufu..)
shimata!- negative slang for shimashita(i did it),as in "oh man... ive done it now...", same meaning as slang word sh*t or cr*p
sukebei- lecher
tsukare nai- literally not useable, useless
urusai- noisy
you can easily make them into curses(if they arent yet) by adding-
inu- dog
ningen- person
saru- monkey
the many forms of i (me)
boku- boy term of i
ore- manly term of i
watashi- universal term of i, usualy girls use it
ware- egotistic term of i
this is why i love the japanese language