Pre 11/9 (or 9/11 as the yanks call it
) I heard of what I'd call an urban rumour.
Some of the guys at an RAAF base had a competition to see who could get through the front gate holding up the silliest item possible to the security guard to drive straight through. The winner held up a half eaten sausage roll, and the security guy let him drive straight through.
I do know of someone who got onto the base during a base "security exercise" with something he drew up with a purple pen.