And "I don't like to say 'I told you so, but...'" This is usually followed by something that might as well be "I told you so!!!"
My friends and family all know me well enough not to say that sort of thing. If someone I don't know well says that, I simply cut them off mid-sentence and say "Don't, then." That means don't gossip, don't be rude, don't say "I told you so." Simply, if people feel the need to give a disclaimer then what they are about to say will be offensive. If people feel the need to quantify their statement with "But it was only a joke..." then what they have said is offensive. In both cases, the speaker knows patently well that their statements have offended and upset, therefore whomever they are speaking to has the right to cut them off mid-tirade if that is the only way to stop them.
I say this simply because there was one particular person who used to say this constantly. Not just to me, but to everyone. "I don't mean to be rude, but..." You could bet your bottom dollar that she would be rude. Very rude. Commenting on people's weight, appearance, etc. Even before eHell, I used to "bean dip" people, changing the subject, which would lead to her saying "You don't like the truth, do you?" Yes, actually, I do like the truth, rather a lot as it happens, just not when it is presented to me in such a manner as to humiliate and upset me. I tried distracting that person as you would a child, I tried talking to her about it and I tried ignoring her in public. Nothing worked. So I just started cutting her off halfway through. I then moved jobs and now have nothing more to do with her or her rude ways. Maybe not the eHell approved way to deal with people like this, but this was after months of her being like this to me. I couldn't get up and walk away as I was sitting opposite her. My manager sat next to me so she could hear everything and when I started cutting her off mid flow, I was the one who got told off for being rude!!