YOU SAID:

Once upon a time I did a gigantic diarrhea on my cousins bed

INTO JAPANESE

昔、いとこのベッドでひどい下痢をしたことがある

BACK INTO ENGLISH

I once had bad diarrhea in my cousin's bed

INTO JAPANESE

私はかつていとこのベッドでひどい下痢をしたことがあります

BACK INTO ENGLISH

I once had bad diarrhea in my cousin's bed