The only Japanese I know is "Baka" (Idiot).
For German, the kind you could really use and they don't teach you in school:
Scheisse - Shit, Fuck, Son of a bitch! (German has a lot of meanings to different words) Pronounced "Shy-Zuh"
der Dummkopf - Numbskull - Pronounced "Dare Doom-Kohpf"
der Trottel - Half Wit - Pronounced "Dare Tro-tel"
Arschloch - Asshole - Pronounced "Arsh-LohCH" (The CH is this word is pronounced by doing that sound that sounds like you're about to spit. The CH in German can be either a "Shh" sound by using your Tongue to touch the roof of your mouth and sound like you're hissing like a Cat, and then sometimes it has the Phlegm sound of Arabic).
der Scheisskerl - Shit head - Pronounced "Shyzz-Kurl" and can be spelled with that Letter in German that looks like a big "B" but with lines.
Ach du Scheisse! - Oh shit! - Ach (Use Plegm) then "do" and then "ShyZuh"
Du kannst mich mal am Arsch Lecken! - Go fuck yourself! - Literal meaning is "You can lick my ass" and you could also just say "Du Kannst mich mal!" and it's the same. To pronounce :
Do Kahnst mich "Mall" "Ahm" "Arsh" "Lecken".
The word Mich is pronounced with the ch sounding like a Cat Hissing by pressing your tongue on the roof of your mouth as before, and basically Blowing air out, the sound should almost be like a Hiss.
das ist mir Scheissegal! - I don't give a shit! - Pronounced like this:
"Dass" "Ist" "Meer" "Shyz-Agel".
Verpiss Dich - Fuck off! - Literally means "Piss yourself away!" - To pronounce:
"Vare-Piss - Dich"
One of the strongest most foul things you CAN say in German, is this:
Das Geht dich einen absoluten Scheissdreck am! - That is none of your fucking Business! -
There are hardly ANY words in German that can be taken or used THIS strong, so if you say this in German, be prepared for a fight, because this is worse than saying you want to rape their child for the occasion it's used in! When you're telling someone to mind their business, and you say this, it doesn't get stronger!
To Pronounce:
Dass Gayt Dich Eye-nen Ahb-so-looten Schyz-Dreck Ahhm
Use with caution!
Scheiss Drauf - Forget it - Literally "Shit on it" - To pronounce:
Shyz-Drowwf. In German "AU" without an Umlaut (Those two dots above a letter, are an Umlaut, and they change how something sounds) but "au" is pronounced "Oww" like when you stub your toe.
der Krug / der Humpen - What we call a "Stein" as Germans don't actually say Stein for a glass, Stein in German means "Stone" and to pronounce these words for Beer Glass:
Dare Kroog and "Dare Hoompin".
das ist nicht mein Bier - That is not my cup of Tea - To pronounce -
Dass ist Nicht Myn Beer
Also note I don't use a Capitol Letter for "das" or "die" or "der". The reason is it's not proper to. And all three words mean "The".
German uses Sexes for Nouns and so on, and a sexless object or thing, has "das" where as a Manly Masculine item is "der" which is pronounced "Dare" and then for something more feminine you would say "die" which is pronounce "Dee".
So how do you tell someone to stop talking? Like this!
Ruhe Bitte - Quiet Please! - Pronounced like this:
"Rooha Bittuh" Because if a word has an "E" at the end, it's pronounced with an "uh" sound.
Halt den Mund! - Keep your mouth shut! - Halt den Moond.
Halt die Klappe! - Shut up! - Halt Dee Klah-puh.
Halt's Maul! - Shut the fuck up! - Halt's Mowwl. Like "owwww I stubbed my toe".
How do you fuck? Like this:
Bumsen - To fuck. The most common "Vulgar" way of saying you want to fuck someone. When a new American Pie came out I was very shocked to see they took a bunch of letters from other languages that all meant sex, like, in Spanish they said "sesso" and so on....Well got German they said Bumsen.... I don't think they realized it meant fuck not screw.
Voegeln - To fuck - Literally - Mating like Birds. Very Popular, has a long history. To pronounce - "Vurl-geln" (The Voe part is hard to say in English because English has NO equivalent at all. The OE part is actually an Umlaut O, but if you can't make the two dots, you can just add an E to say "Pretend this has an Umlaut".
Ficken - To fuck! Originally it meant simply to move back and forth, or to rub, but no one uses it this way anymore. You can see it's related to fuck.
Blasen - to Blow. Pronounce like this:
"Blah-Sen".
Wichsen - To jack off - Pronounced like this:
"Vich-sen".
die Hobbyflecken - Slang for Semen stains.
Kommen - To come.
das horizontale Gewerbe - Prostitution - Literally means "The Horizontal Business".... Lol. To Pronounce -
dass Horits-ohn-talluh Gay-Vaarbuh.
Enjoy