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.

The Lord Commander
told us to go to the Fist of the First Men.
Game of Thrones Season 3, Episode 4

I am not FIST bumping
you after we have sex.
The Big Bang Theory Season 11, Episode 8

The Fist of the First Men.
Game of Thrones Season 3, Episode 2

and had decided to bang
his FIST on the table
Money Heist Season 1, Episode 7

The Fist of the First Men.
Game of Thrones Season 2, Episode 5