The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

It's a scaly genital ORGAN
that grows between his shoulder blades.
The Big Bang Theory Season 8, Episode 8

...to the male sex ORGAN.
The Big Bang Theory Season 3, Episode 2

Well, some people think
the sexiest ORGAN is the brain.
The Big Bang Theory Season 9, Episode 8

Like an ORGAN
that's not a perfect match.
Westworld Season 2, Episode 4

...I am betrayed by my appendix,
a vestigial ORGAN.
The Big Bang Theory Season 4, Episode 2