Quote Originally Posted by zero2104
duude, just tell him u overheard them saying shit like that, and tell him u swear that u wont tell anyone, and maybe it was a lie

Are you serious? Do you know how embarrassed his friend is going to feel? Maybe even pissed? Betrayed?

I would definitely tell your friend that "so and so is talking shit about you" (depending on how close you and your friend are) but I wouldn't tell him what you heard in details. If anything, I would let the girl with the big mouth know that you wouldn't trust her with any secrets. Like someone said, it may all be a lie.