YOU SAID:

i believe i have shat upon my pantaloons

INTO JAPANESE

私は私のパンタロンに shat 持っていると思います

BACK INTO ENGLISH

I think I have shat in my pantaloons

INTO JAPANESE

私は私のパンタロンで shat 持っていると思う

BACK INTO ENGLISH

I think I have shat in my pantaloons