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.

Can't you be a little bit FLEXIBLE?
The Big Bang Theory Season 2, Episode 16

for the wrinkled,
but still FLEXIBLE, Madonna.
The Big Bang Theory Season 7, Episode 18
![[Russian accent]:
Flexible men and women.
[Russian accent]:
Flexible men and women.](data:image/png;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=)
[Russian accent]:
Flexible men and women.
The Big Bang Theory Season 12, Episode 5

He also invented the Franklin stove,
bifocals and the FLEXIBLE urinary catheter.
The Big Bang Theory Season 3, Episode 6

Oh, of course.
I'm nothing if not FLEXIBLE.
The Big Bang Theory Season 12, Episode 20