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.

Stale pastry is hollow succor
to a man who is bereft of ostrich.
The Big Bang Theory Season 4, Episode 19

The competition has become a bit STALE.
Game of Thrones Season 1, Episode 1

Piña colada?
More like STALE bubblegum.
Breaking Bad Season 4, Episode 7

Do you have any STALE ones from yesterday?
Or any burnt ones?
Game of Thrones Season 1, Episode 9

Yeah, it's delicious.
The sarcasm's a little STALE, though.
The Big Bang Theory Season 3, Episode 17