How to be Insulting in Banks: Try to use one of the automatic cash dispensers, but use it incorrectly. If it's inside the bank, do this until someone is sent to help you out, or until you're asked to leave. If it's outside the bank, kick the machine and try to open it with your car keys, a penknife or your umbrella.
How to be Insulting in Banks: When ordering travelers checks, try to get the smallest denomination available, and then take ages signing each check in front of the cashier.
How to be Insulting in Church: If you just want to look inside the church, go in when you see the sign 'Service in Progress'. Take photographs with a bright flash-gun.
How to be Insulting in Church: Pour water into the font and wash your hands in it. If you're really daring, take off your shoes and socks and cool your feet.
How to be Insulting Abroad: Insist on paying for everything in sterling.