I have no idea how to help you overcome your apparently severe ticklishness, perhaps therapy would offer some useful insight.
I don't know how often you are approached by people wielding a "vibration device," but I would try yelling, in a very loud and forceful tone of voice "NO!" Or "STOP! I DO NOT LIKE THAT!"
If that does not stop them, since you find this not only embarrassing but actually PAINFUL, then these people have crossed the line into physical abuse and should be reported to the authorities.
You can either stop having people cut your hair with the electric clippers,
or you'll just have to have your hair trimmed w/ scissors. My son has the same reaction as you, now he goes to a barber who uses a straight razor.
Good Luck :)