YOU SAID:
my brother got peed on by a bat
INTO JAPANESE
私の兄はバットにおしっこをかけられました
BACK INTO ENGLISH
my brother was peeed on the bat
INTO JAPANESE
私の兄はバットにおしっこをされました
BACK INTO ENGLISH
my brother was pissed on the butt
INTO JAPANESE
私の兄はお尻に腹を立てていました
BACK INTO ENGLISH
my brother was pissed in the ass
INTO JAPANESE
私の兄はお尻に腹を立てていました
BACK INTO ENGLISH
my brother was pissed in the ass
That didn't even make that much sense in English.