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.

"This includes boxers, BRIEFS,
thongs, G-strings
The Big Bang Theory Season 10, Episode 13

...I suggest you switch
from BRIEFS to boxers.
The Big Bang Theory Season 4, Episode 18

- Maybe she's his lawyer.
- Well, she's free to examine my BRIEFS.
The Big Bang Theory Season 1, Episode 15