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.

I'm the BOSS. I make the jokes.
The Big Bang Theory Season 3, Episode 4

My BOSS says you have to either
order or leave and never come back.
The Big Bang Theory Season 1, Episode 5

lf the BOSS wants them
to drink,
Breaking Bad Season 4, Episode 8

when you knew
your BOSS had asthma?
The Big Bang Theory Season 11, Episode 8

- You have to call the BOSS.
- I already did.
Westworld Season 2, Episode 8