YOU SAID:
I had a party in your pants
INTO JAPANESE
あなたのズボンでパーティーをしていた
BACK INTO ENGLISH
Had a party in your pants
INTO JAPANESE
あなたのズボンでパーティーをしました。
BACK INTO ENGLISH
Had a party in your pants.
INTO JAPANESE
あなたのズボンでパーティーがありました。
BACK INTO ENGLISH
Had a party in your pants.
That didn't even make that much sense in English.