YOU SAID:
Don't be a party pooper.
INTO JAPANESE
盛り上がってはいけません。
BACK INTO ENGLISH
Should not be raised.
INTO JAPANESE
発生しませんする必要があります。
BACK INTO ENGLISH
No need to.
INTO JAPANESE
いや そんなことする必要はない
BACK INTO ENGLISH
No need to.
You've done this before, haven't you.