How to be Insulting in Hotels: Call room service last thing at night, when the kitchens have just been locked, and ask for a cheese sandwich and a glass of fresh milk. Make sure that you leave them untouched and conspicuous the next morning.
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: Arrive late for any service and arrive noisily. Forget at least one, if not both books, and try to make others stand up while you go back for the ones you need.
How to be Insulting at Christmas: Try to duplicate presents wherever possible then lose the receipts so that none of them can be exchanged. If they happen to be things you want yourself, so much the better. Just offer to take them back.