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
That didn't even make that much sense in English.