I can just imagine Nami trying to teach Luffy the concept of 'discretion' and giving up after a matter of moments with a giant a headache. Or maybe pulling out a notepad for blackmail purposes, because Luffy is soooo the kind of guy who'd say "Oh, you mean how Zoro told me not to tell anyone that he enjoys xxxxxxxx" when someone tells him how important it is to keep secrets. XD