Great question and I also got an answer.
HECKLERS- A magicians worst enemy
I got one simple tip for you for dealing with a heckler, Just stop performing, make up whatever reason you have to and just get out, if they don't want to enjoy the entertainment you are giving them then don't waste your time on them and go find somone that is more co-operative.
You can usually tell which type of people are the heckling typ. They are usually the onces with the big mouth and trieing to get the centre of attention.
Hope this helps you all out a bit more.