YOU SAID:

You gotta be kidding. I'm gonna use the bathroom.

INTO JAPANESE

冗談でしょ。私はトイレを使うつもりです。

BACK INTO ENGLISH

You're kidding me. I'm going to use the toilet.

INTO JAPANESE

冗談を言ってますよね。私はトイレを使うつもりです。

BACK INTO ENGLISH

You're kidding. I will use the toilet.

INTO JAPANESE

冗談を言ってますよね。トイレを使います。

BACK INTO ENGLISH

You're joking, aren't you? I use the toilet.

INTO JAPANESE

冗談でしょ?私はトイレを使います。

BACK INTO ENGLISH

Are you kidding me?

INTO JAPANESE

冗談でしょう?

BACK INTO ENGLISH

Are you kidding me?