YOU SAID:
He went to the bathroom and I peed in his drink.
INTO JAPANESE
彼はトイレに行き、私は彼の飲み物でおしっこしました。
BACK INTO ENGLISH
He went to the bathroom and I peeed with his drink.
INTO JAPANESE
彼はトイレに行き、私は彼の飲み物でおしっこしました。
BACK INTO ENGLISH
He went to the bathroom and I peeed with his drink.
This is a real translation party!