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.

-Stop it.
-Who was this guy with the MOUSTACHE?
Money Heist Season 1, Episode 1

You mean a MOUSTACHE?
The Big Bang Theory Season 7, Episode 16

...threatening that little prissy guy
with the MOUSTACHE.
Breaking Bad Season 3, Episode 13