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 at Christmas: Buy crackers without any little gifts inside. If you have the time beforehand, put unpleasant little remarks and observations inside them instead. You might try to glue the paper hats together so that they tear when the guests try to open them.
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 in Church: Always try to be half a line ahead of the vicar, and always be as loud as you dare in the responses.
How to be Insulting on the Beach: If there's enough sand, dig huge walls around your site and try to put your neighbors in the shade.