YOU SAID:

i pooped my pants and its run down my leg

INTO JAPANESE

私は私のズボンをうんちし、それは私の足を走りました

BACK INTO ENGLISH

I pooped my pants and it ran down my leg

INTO JAPANESE

ズボンをうんちしたら、それが足に流れ落ちた

BACK INTO ENGLISH

I pooped my pants and it ran down my leg