YOU SAID:

the lion had a party and pooped his pants

INTO JAPANESE

ライオンはパーティーをしてズボンにうんこをした

BACK INTO ENGLISH

The lion had a party and pooped in his pants

INTO JAPANESE

ライオンはパーティーをしてズボンの中にうんこをした

BACK INTO ENGLISH

The lion had a party and pooped in his pants