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.

And before that, he was a JOLLY fellow,
Game of Thrones Season 5, Episode 7

He was such a JOLLY little fellow.
Game of Thrones Season 3, Episode 10

isn't Broccoli Hulk basically
just the Jolly Green Giant?
The Big Bang Theory Season 12, Episode 20

Jolly amusing. But if you don't mind,
I'll hold off until sunset on Titan.
The Big Bang Theory Season 3, Episode 4

To make things more JOLLY, there were
so many blinking lights on the house...
The Big Bang Theory Season 3, Episode 11