YOU SAID:

I have a semi-large erection

INTO JAPANESE

私は半大きな勃起を持っています。

BACK INTO ENGLISH

I half has a big erection.

INTO JAPANESE

私は半分大きな勃起を持っています。

BACK INTO ENGLISH

I has half a big erection.

INTO JAPANESE

半分、大きな勃起があります。

BACK INTO ENGLISH

Half a large erection.

INTO JAPANESE

半分は大勃起。

BACK INTO ENGLISH

Half a large Boner.

INTO JAPANESE

半分は大勃起。

BACK INTO ENGLISH

Half a large Boner.