Free Private Preston!
...was what you could read as graffiti at a couple of places in Washington, D.C. after he stole a Huey and landed it on the White House lawn in the early Seventies.
From what I remember Private Preston was a helicopter crew chief who had not made the cut to be trained as a helicopter pilot in the U.S. Army and this was his way of showing everyone that he could too fly helos to a reasonable standard!
When he landed on the lawn a Secret Service man shot him with a 12-gauge. Then he was taken off to be tried and sent to Fort Leavenworth to turn rocks into gravel or whatever it is you have to do when the Army is very, very unhappy with you. After that one Army helos were fitted with ignition switches, I think.
I heard that one of our crew chiefs (holder of a civilian pilot's licence) in Viet Nam, down in Can Tho I think, took an RU-8D (the military version of the BE-50 Twin Bonanza) around the pattern one evening on a dare with no-one the wiser. The story made the rounds of the enlisted men but must have not awakened any official interest, plus it would have been pretty embarrassing to publicise some Specialist Fifth Class taking a bird crammed with top-secret gear on a flip around the pattern like that.