What to do when someone backbites

Many a times you come around people that either bad mouth about you behind your back or put their foot in things that are of absolutely no concern to them... And the this leaves you hurt.. I am not sure if I know many of such people and even if they are around me, they are pretty good at it at what they do cause I have no clue about their existence. But the question is that if you do happen to be the victim in such a scenario, what to do?

The first thing that comes to mind is to let go... just don't care about what who said and have a don't care attitude towards such a thing. Although this is probably the best solution, it isn't the easiest thing to do. So, what else can be done.

One option would be to go to the person meddling around and say very clearly and sternly, dude, keep your trap closed.
The other option, more cultivated, is to take the person to a corner and tell him that what he's doing ain't right and it hurts cause it is not what I expect from you. I am sure if the person is doing it just to get some kicks out of it, then, he will stop. The other kind of people will never change, but, they will atleast be aware that they aren't as smart as they thought they are.

Which one do I choose? None! I'll go backbite as well :P