Fixed, thank you!

I agree. To that same list you can add “hip” vocabulary found in textbooks that the authors (who are probably not young) thought sounded like cool youths, but actually was quite old even when the textbook was published a few years ago. There are so much else to learn and focusing on the core vocabulary gives you much more value. Learning and picking up slang naturally in context is something else, but that won’t happen unless your level is already quite advanced.

Internet slang gets obsolete, quick. All your base are belong to us, anyone? LOLcats? Three Wolf Shirt? Much better to spend your time on vocabulary that doesn’t change. Unless you’re one of those magnificent speakers who has apparently unlimited time and an astounding memory.