One of the great responders to heckling was Tony Capstick.
I well remember a night at Poynton folk club. (If anyone can't remember, it used to have regular audiences of about 300 people).
A smartarse bawled out 'ere Capstick, can yer open yer gob any wider'.
Without a pause for breath, Tony replied 'open yours a bit wider mate, and I'll park me van in it.'
Pure artistry.
Roger