Talking about someone behind their back gets a bad rep. Here's how I see it: so long as the conversation entertains all those involved, no one repeats what is said to the person at hand, and you don't treat the person at hand differently based on your personal judgement, it's harmless. More than harmless, it's causing joy. Not a bad thing in my opinion. No one should give a damn what is said about them in conversations they aren't privy to. If someone so chooses to discuss their opinion of me with someone else, more power to them. I just hope that conversation gets a few laughs at my expense.