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.

If we let him BUCKLE our
center, he'll pursue.
Game of Thrones Season 6, Episode 9

Ooh, look, a new Batman belt BUCKLE.
The Big Bang Theory Season 2, Episode 20

Says the man with a giant
belt BUCKLE and a dickey.
The Big Bang Theory Season 12, Episode 6

It's a light saber
belt BUCKLE.
The Big Bang Theory Season 12, Episode 24

All right. Let's BUCKLE down and work.
The Big Bang Theory Season 3, Episode 4