Well my favourite for the persistent heckler who 'knows' how every trick is done is to do my lighter and bank note routine for them.
You ask them to produce a large denomination note (larger the better) like a 20 or 50. You then ask to borrow a lighter or give them your own. Get the heckler to note down the serial number of the note and then ask them to set light to the note with the lighter, wink at them while doing this. Because you have already preformed some (amazing) feats of magic, people are lulled into a very false sense of security and will go along with things and do things that they would not normally do. So if all goes well the heckler will set fire to his own bank note. (it helps a lot if they are drunk, which they usually are). Then say to the heckler, "now restore the note by taking the ashes in your hands and squeezing tight. Now open your hands" of course the note is still burnt as there is no way of restoring it. look at them in a puzzled way and say "I thought you knew how to perform magic?" Look disappointed in them and then depending on how the crowd is reacting get ready to move on, finish or RUN.
If the heckler is still persistent then I go into my "borrowed lighter and hecklers hair" routine, that always gets a few laughs.
MajikBoris aka Mark the Magician
A power that must only be used on 230V a/c.
MajikBoris, Are you serious ?
That sounds like the best way to become hated and beaten up. If it was a dollar bill or something then MAYBE that would be clever but a 20 or 50 ?
No heckler deserves to be the target of a $50 loss to satisfy your annoyance at his interruption. Clearly they are expecting you to help and do something magical because i doubt they actually think they can restore it using their own 'magic powers'.
What if they need that money ?
If you want to take a persons money and make them look like an idiot that just lost $50 and you don't care if they are upset or annoyed or hate your guts (which they probably will and might even punch you in the head to show it) , make their note disappear and then give it to charity. Don't let people burn their own money which they might have worked really hard to earn simply because they are annoying you.