I have a close friend who takes great sport in occasionally seriously misleading me, much as described in
Are you being perfectly honest?
except inasmuch as what she says is never completely unbelievable and is frequently quite credible. (.. or else I, being quite close to her, am the credible item in this equation.)
Really? is the key phrase triggering dissemblance - until that point any number of supporting falsehoods are considered fair game.
Because the suspicion of a malicious friend is not always the first thing to come to mind in instances of particularly terrible news (Wow. Is there going to be a public service? / You know, somehow I'm not surprised that your best friend slept with your boyfriend.) I occasionally serve as a high water mark on how credible her own suspicions are when she feels she might be getting a bit paranoid.
Occasionally, however, I pull the really? on something which is not only true but has been previously established, which never fails to blow holes in her faith that I pay attention to what she says. Ah, the pitfalls and dangers of common conversation. Always more challenging but not always more rewarding than just falling asleep on the phone together.