"Just kidding" isn't cutting it in Iran, demonstrated by their refusal to laugh off John McCain's joke that the rising U.S. cigarette exports to the Islamic Republic may be "a way of killing 'em." McCain has surely not been their favorite comic for some time, likely dating back to his having sung in jest about bombing their country.
I, too, am never appeased by, "just kidding," finding it lame, unconvincing, a follow-up offense from someone trying to deny responsibility for a hostile remark that was not amusing. When a line is truly funny, the listener identifies it as a joke. We've all experienced the frustration of confronting a person about a hurtful comment only to be dismissed by, "I was just kidding." It's a response that's not even as reflective as, "my bad." Far better to listen, learn and express genuine remorse.
McCain, if he can work up some more anti-Iranian material, may be able to get a recording contract and show on al-Jazeera. Just kidding!