Someone was asking about a romaji version

So I'm going to translate as best as I can

For your benefit and for my practice

Damn!
くそ！

Kuso!

Gee!
えぇ！へぇ！

Ee! Hee!

I don’t give a shit.
かんけいないね

Kankei nai ne

("It doesn't matter")

I do give a shit!
かんけいあるよ！
Kankei aruyo!

Don’t fuck with me!
ふざけるな

Fuzakeruna

Good luck!
がんばって

Gambatte

Gotta go
行かないと

ika nai to

Have a nice day.
We do not say this in Japanese.
We just say “またね” as in “see you” instead

Mata ne

I envy you.

いいなぁ/うらやましい

iinaa / urayamashii

It’s like...
なんか/ってゆうか

nanka... / -tte yuuka

It’s hard to say but…
言いにくいんだけど…

ii nikuin da kedo...

Like I said...
(いまor さっき or まえに）言ったように

(ima / sakki / mae ni) itta you ni

(now / a little while ago / before)

いってらっしゃい
itte rasshai
See you later / Take care
(When someone is leaving)
<em>(it is more like "bon voyage")</em>

いただきます
itadakimasu
We say this before eating

おかえり
okaeri
Hi
(When someone comes back)
<em>(more llke "welcome back!")</em>

おつかれ
otsukare
Thanks for your hard work (as a greeting)
Good bye

おまたせ
omatase
Thank you for waiting
Sorry to have kept you waiting

ごちそうさま
gochisousama
We say this after eating

しまった！
shimatta
Oh shit! / Damn it!
<em>(more like the "damn it" you would say instead of "oops". not a "damn it, bobby!" kind of thing)</em>

じょうだんだよ
jiyou dandayo
I’m kidding!

ただいま
tadaima
I’m back!
(You can say it when you return from somewhere)

しんどい
shindoi
This is tough!
<em>(more like "this is tiring")</em>

ちょっとね
chotto ne
Yeah, well…you know.

とにかく
tonikaku
Anyway

とりあえず
toriaezu
For now

ね？/でしょ？
ne? / desho?
Isn’t it?

びみょう
bimyou
Subtle / Iffy *

ヤバイ
yabai
Big trouble! / Oh shit!

Take care!
じゃあね / きをつけて *
jyaa ne / ki o tsukete

That sounds good to me.
いいんじゃない？
iin jyanai?
<em>(it is more like "why not?" i.e. as "you wanna go to the mall?" "sure, why not?")</em>

<em>
</em>

There you go again.
はじまった/ でた
hajimatta / deta

You did it!
やったね！
Yatta ne!
<em>(or just straight up "YATTA!" Hiro style)</em>

<em>
</em>

You scared me.
びっくりした
Bikkuri shita

What?
え？/ なに？
E? / Nani?

What’s going on?
なになに？
Nani nani?

What’s new?
さいきんどう？
Saiki n dou?

Wow!
すごい！
Sugoi!
<em>(also means "great!" or "amazing!")</em>

* We do not say きをつけて (ki o tsukete) when writing letters. We say that only the situation on the street when we say “bye”. In letters, we say just じゃあね (jyaa ne) as in “see you” or じゃあまた (jyaa ma ta) as in “see you again”.

これらの言葉をアニメやドラマからとっくに知っています。

すばらしいい！

Doesn't くそ also means shit?