YOU SAID:

Hello, my name is stuffundefined

INTO JAPANESE

こんにちは、私の名前はstuffundefinedです

BACK INTO ENGLISH

Hello, my name is stuff undefined

INTO JAPANESE

こんにちは、私の名前は未定義のものです

BACK INTO ENGLISH

Hello, my name is undefined

INTO JAPANESE

こんにちは、私の名前は未定義です

BACK INTO ENGLISH

Hello, my name is undefined