YOU SAID:

Superman wears underpants outside his pants.

INTO JAPANESE

スーパーマンはズボンの外側にパンツを着る。

BACK INTO ENGLISH

Superman wears pants on the outside of the pants.

INTO JAPANESE

スーパーマンはズボンの外側にズボンを着る。

BACK INTO ENGLISH

Superman wears pants on the outside of the pants.