Ok, so maybe pig latin will make you bilingual, can you speak it fluently?
Profanity! I should have added that to my list of languages too! (Actually, my favourite profanity is in German, LOL.. Every other word I hear in Germany is scheiße!).
No seriously though, it has been a great help being trilingual. German got me by in Germany. French sort of helped me in Quebec, but not really... strange, I thought I'd pick up on Quebecois being a french speaker myself, didnt ever happen LOL.