Quote from Chandler in The One Where Rachel Tells...
Monica: I didn't think you could keep it a secret. Chandler: [high-pitched voice:] What? [normal voice:] I am an excellent secret-keeper. I have kept all our secrets. Joey: What secrets? Chandler: No, no, Joey. I'm not gonna tell you because I am an excellent secret-keeper. Joey: Psst. You'll tell me later? Chandler: You already know.