After you register (which literally takes 10 seconds (no email confirmation link)...you can add anything...it's easy and quick...also after you register you can create a profile, message other users, and join/create posses.
There's a ton of stuff (words, tricks, slang, places, etc.) we don't have because user's have'nt added them yet. So take the word jib for instance...once registered (free, takes l0 seconds) you can add that word, define it, then throw a pic or vid of someone (or yourself) jibbin a rail into the entry. If you guys see anything that isn't there add it!