usage - What does っつの mean?

I recently saw 冗談だっつの. What does it っつの mean, or how does it modify the meaning of a sentence?

Answer

っつ (sometimes つう) is a slang version of という (or an alternate version like といった, depending on the context). It's extremely informal.

冗談【じょうだん】だっつの。 (＝冗談だ【じょうだん】といったの。) I said I was joking. [Idiomatically: Chill out, I was just kidding.]

彼【かれ】はやめたいっつってんだから、やめさせてやりゃいいじゃん。 (＝彼【かれ】はやめたいといっているんだから、やめさせてやればいいじゃない。) He's saying he wants to quit, so why not let him?

まぁ、なんつうかさ、ちょっとまずいっすね。 (＝まぁ、なんというかさ、ちょっとまずいですね。) Well, it's…what should I say…kind of a bad situation.