YOU SAID:

I had a party in my pants

INTO JAPANESE

私はズボンでパーティーをした

BACK INTO ENGLISH

I had a party with my pants

INTO JAPANESE

私のズボンとパーティーをしていた

BACK INTO ENGLISH

Had a party with my pants

INTO JAPANESE

私のズボンとパーティーがありました

BACK INTO ENGLISH

There was a party in my pants with

INTO JAPANESE

私のズボンでパーティーがありました

BACK INTO ENGLISH

Had a party in my pants

INTO JAPANESE

私のズボンでパーティーをしました。

BACK INTO ENGLISH

Had a party in my pants.

INTO JAPANESE

私のズボンでパーティーがありました。

BACK INTO ENGLISH

Had a party in my pants.