How to be Insulting in Church: Sing out of tune in all the hymns and try singing half a line behind everyone else.
How to be Insulting on the Beach: Try to find seaweed and drag this along the beach, leaving bits beside other people's places.
How to be Insulting in Banks: Take a tape recorder with you to the meeting with the manager. Say nothing the entire time, but simply record all he says to you. Then when he's finished play it back to him at twice the speed and leave.
How to be Insulting on the Beach: Buy several large newspapers, and leave these lying around so that they blow all over the beach.
How to be Insulting on the Beach: Sit by the water with a fishing rod, and throw revolting lumps of old bread into the water where the children are enjoying themselves.