YOU SAID:

i farted so loud i pretty much pooped my pants

INTO JAPANESE

おならの音が大きすぎて、パンツにうんこが出そうになった

BACK INTO ENGLISH

The fart was so loud that I almost pooped in my pants

INTO JAPANESE

おならの音が大きすぎて、ズボンの中にうんこしてしまいそうになった

BACK INTO ENGLISH

The fart was so loud that I almost pooped in my pants