Dirty Japanese: Everyday Slang Book - Learn Casual Japanese Phrases & Modern Slang for Travel, Anime & Manga Fans | Perfect for Language Learners & Japan Enthusiasts

First off, this book is about 90%~ accurate. In the sense that some of the material is dated, but that's expected with any slang book. Slang comes and goes. For the most part though, the author clearly labels some dated slang. The author also points out a lot of Japanese cultural background and other very useful information. I would say this is a very useful book since it does deepen your understanding of Japanese slang and culture.If you're wondering if a particular slang word / phrase is dated, simply ask a Japanese friend. Don't just flame the book. There's no slang book in the world that will be 100% accurate because slang is constantly changing. I'm sure you know a LOT of dated slang in your own language. While they may seem 'useless' they can be awesome for jokes.