Rules for dealing with nutters.
1. Never, never, ever make eye contact.
2. Never, never, ever, try to debate, discuss, explain or in any other form communicate with them beyond trying out some Monty Python routines. See Rule 1.
3. Never, never, ever argue with a fool, all that will happen is they will drag you down to their level and beat you with experience. Worse, onlookers might not be able to tell the difference.
4. Life is too short, smile, nod sagely and look like you know something they don't and zip it. It drives em crazy.