Best way to learn the local slang nobody teaches in class?

Fatou, Irish English was a whole second language for me after I thought I spoke English well. "What's the craic" is a greeting, "giving out" means complaining, and "I will, yeah" means absolutely not. What helped most wasn't a book. It was the local radio in the car, listening to people ring in and complain about the traffic and the weather. Two months of that did more for my ear than two years of school English. And asking colleagues to explain the phrases they used, which they loved doing.

dutch slang from my colleagues at lunch. they think it's hilarious to teach me the worst words first. i'm learning, just not the useful ones

Anna, "I will, yeah" meaning no took me a full year to understand. I thought my landlord was agreeing to fix things.

Sport, again. The Gaelic football club I joined taught me more real Irish English in two months than anything else. People talk differently on the pitch and in the pub afterwards than they do at work, and nobody minds if you ask. My favourite discovery so far: "grand" can mean anything from brilliant to disaster, as Olena says in another thread, and the tone is the only clue.

ok the radio idea is great, never thought of it. and asking colleagues to explain instead of pretending to understand. thanks all, starting monday