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.

Professor Woo.
The Big Bang Theory Season 6, Episode 20

Woo!
The Big Bang Theory Season 7, Episode 6

Your inability
to successfully WOO Penny...
The Big Bang Theory Season 1, Episode 14

Oh, not you, Dr. Woo.
You're fine.
The Big Bang Theory Season 7, Episode 6

the pitching of WOO.
The Big Bang Theory Season 11, Episode 11