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.

I hear that you're a PERVERT.
Game of Thrones Season 3, Episode 10

he's the PERVERT pulling the strings here.
The Big Bang Theory Season 10, Episode 5

it happens that Mr Pervert Pimpin here
has turned into a betrayer,
Money Heist Season 1, Episode 11

Pervert.
The Big Bang Theory Season 7, Episode 7

GOMEZ: You wanted her
to bang a football player,
you big, bald PERVERT?
Breaking Bad Season 2, Episode 3