YOU SAID:

My brother is a party pooper

INTO JAPANESE

私の兄はパーティーの下手人です

BACK INTO ENGLISH

my brother is a bad party guy

INTO JAPANESE

私の兄は悪いパーティー好きです

BACK INTO ENGLISH

my brother is a bad party lover

INTO JAPANESE

私の兄はパーティーが苦手です

BACK INTO ENGLISH

my brother doesn't like parties

INTO JAPANESE

私の兄はパーティーが好きではありません

BACK INTO ENGLISH

my brother doesn't like parties