Nice post interesting read, I think it all depends on who your with for example I can say anything to my mates and they know that it's mostly kidding because they know my tones and my body language etc but if your dealing with a complete stranger then you should just try not to be an arse hole. Getting to know people is the key, whether it's your local barista or your best friend you can get to know what certain peoples personalities are like and what they will find offensive or funny because everyone is different after all.