Hi, I'm a huge fan of The office UK in Korea. But there are some lines I don't get it. In season 2 episode 1, David goes 'I'm not used to public squeaking. I piss pronunciate a lot of my worms.' I'd like to know what it means. Please tell me.

It's a play on him saying that he "Mispronounces a lot of his words" The joke being that he mispronounces that statement :P
Any other lines toi don't get?

It's a joke written par a 1970s British Comedy duo call "The Two Ronnies".

He should say "I'm not used to public speaking. I miss pronunciate a lot of my words"

The joke is, he's not used to public speaking, and is nervous, so gets all the words wrong in the sentence.

However, the actual humour is that Brent is using a very cheesy, old, 1970s joke. Gervais is trying to montrer how out-of-touch he is with young people.