Seems kinda risky... how can you be sure they told the the right words? More so, sometimes words can sound very similar, so you could end up saying something quite different that what you thought.
Ed
Hey, we were all just a bunch teenagers barely speaking English, ripped out of our natural environment (and country). We were like a family of foreigners in in the same class - we weren't about to be messing with each other.
But you are right -- trust no one! Just like that American guy who trusted his tattooist to tattoo a Chinese symbol for "mother", but he really tattooed a Chinese symbol for "F-U".
We are a bit paranoid? Maybe just stick with your native tongue.
Anyway, all the dirty words I learned were correct (I verified them later), and I can even pronounce them in Vietnamese.